Namespaced, unit + functional tests, PSR2, Makefile...

28 files changed, 2663 insertions, 900 deletions

diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..3e6f051
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,24 @@
+# This file is for unifying the coding style for different editors and IDEs
+# editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space
+indent_size = 4
+max_line_length = 120
+
+[{.jshintrc,*.json,*.yml}]
+indent_style = space
+indent_size = 2
+
+[*.md]
+trim_trailing_whitespace = false
+
+# Use tabs for indentation (Makefiles require tabs)
+[{Makefile,**.mk}]
+indent_style = tab
diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..396154c
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,13 @@
+# Ignore all test, docs etc with "export-ignore".
+/.editorconfig export-ignore
+/.distignore export-ignore
+/.gitattributes export-ignore
+/.gitignore export-ignore
+/.scrutinizer.yml export-ignore
+/.styleci.yml export-ignore
+/.travis.yml export-ignore
+/phpcs.xml export-ignore
+/phpcs.xml.dist export-ignore
+/phpunit.xml export-ignore
+/phpunit.xml.dist export-ignore
+/tests export-ignore
diff --git a/.gitignore b/.gitignore
index d3bc96c..a5999bb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,8 @@
 nbproject
+phpunit.xml
 tests.php
 composer.lock
 vendor/
+node_modules/
+/.phpcs.cache
+/coverage/
diff --git a/.scrutinizer.yml b/.scrutinizer.yml
new file mode 100644
index 0000000..c97fc42
--- /dev/null
+++ b/.scrutinizer.yml
@@ -0,0 +1,41 @@
+filter:
+    paths: ['src/*']
+
+checks:
+    php: true
+
+tools:
+    external_code_coverage: true
+
+build:
+    nodes:
+        analysis:
+            environment:
+                mysql: false
+                postgresql: false
+                redis: false
+                mongodb: false
+                elasticsearch: false
+                memcached: false
+                neo4j: false
+                rabbitmq: false
+                php:
+                    version: 7.1
+            cache:
+                disabled: false
+                directories:
+                    - ~/.composer/cache
+            project_setup:
+                override: true
+            tests:
+                override:
+                    - php-scrutinizer-run
+
+#
+#build_failure_conditions:
+#    - 'elements.rating(<= C).new.exists'                        # No new classes/methods with a rating of C or worse allowed
+#    - 'issues.label("coding-style").new.exists'                 # No new coding style issues allowed
+#    - 'issues.severity(>= MAJOR).new.exists'                    # New issues of major or higher severity
+#    - 'project.metric_change("scrutinizer.test_coverage", < 0)' # Code Coverage decreased from previous inspection
+#    - 'patches.label("Doc Comments").new.exists'                # No new doc comments patches allowed
+#    - 'patches.label("Unused Use Statements").new.exists'       # No new unused imports patches allowed
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..397cfd2
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,51 @@
+dist: trusty
+language: php
+sudo: false
+
+cache:
+  apt: true
+  directories:
+    - $HOME/.composer/cache/files
+
+php:
+  - 5.6
+  - 7.0
+  - 7.1
+  - 7.2
+  - nightly
+
+matrix:
+  fast_finish: true
+  allow_failures:
+    - php: nightly
+
+before_install:
+  - mv ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/xdebug.ini{,.disabled} || echo "xdebug not available"
+  - composer self-update
+
+install: travis_retry composer install --no-interaction
+
+script:
+  - find src tests \( -name '*.php' \) -exec php -l {} \;
+  - vendor/bin/phpunit
+
+jobs:
+  allow_failures:
+    - php: nightly
+  include:
+    - stage: Coverage
+      php: 7.1
+      before_script:
+        - mv ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/xdebug.ini{.disabled,}
+        - if [[ ! $(php -m | grep -si xdebug) ]]; then echo "xdebug required for coverage"; exit 1; fi
+      script:
+        - ./vendor/bin/phpunit --coverage-clover ./clover.xml
+      after_script:
+        - wget https://scrutinizer-ci.com/ocular.phar
+        - php ocular.phar code-coverage:upload --format=php-clover ./clover.xml
+      after_success:
+        - bash <(curl -s https://codecov.io/bash) -f ./clover.xml
+    - stage: CodeStyle
+      php: 7.1
+      script:
+        - ./vendor/bin/phpcs -n
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..961e35a
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,28 @@
+# Change Log
+
+## [Unreleased]
+### Added
+- n/a
+
+### Changed
+- n/a
+
+### Fixed
+- n/a
+
+## [1.0.0] - 2017-11-xx
+### Added
+- Namespaced code
+- Unit and functional tests
+- Makefile to handle development dependencies
+- Added Travis CI & Scrutinizer integration
+
+### Changed
+- Switched to PSR2 style
+
+### Fixed
+- Fixed a few edge cases (which tests revealed)
+
+## [0.6] - 2009
+### Added
+- Initial release
diff --git a/LICENSE.txt b/LICENSE.txt
new file mode 100644
index 0000000..63c3050
--- /dev/null
+++ b/LICENSE.txt
@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
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+not impose a license fee, royalty, or other charge for exercise of
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+(including a cross-claim or counterclaim in a lawsuit) alleging that
+any patent claim is infringed by making, using, selling, offering for
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+
+  11. Patents.
+
+  A "contributor" is a copyright holder who authorizes use under this
+License of the Program or a work on which the Program is based.  The
+work thus licensed is called the contributor's "contributor version".
+
+  A contributor's "essential patent claims" are all patent claims
+owned or controlled by the contributor, whether already acquired or
+hereafter acquired, that would be infringed by some manner, permitted
+by this License, of making, using, or selling its contributor version,
+but do not include claims that would be infringed only as a
+consequence of further modification of the contributor version.  For
+purposes of this definition, "control" includes the right to grant
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+this License.
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+  Each contributor grants you a non-exclusive, worldwide, royalty-free
+patent license under the contributor's essential patent claims, to
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+propagate the contents of its contributor version.
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+  In the following three paragraphs, a "patent license" is any express
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+(such as an express permission to practice a patent or covenant not to
+sue for patent infringement).  To "grant" such a patent license to a
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+patent against the party.
+
+  If you convey a covered work, knowingly relying on a patent license,
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+to copy, free of charge and under the terms of this License, through a
+publicly available network server or other readily accessible means,
+then you must either (1) cause the Corresponding Source to be so
+available, or (2) arrange to deprive yourself of the benefit of the
+patent license for this particular work, or (3) arrange, in a manner
+consistent with the requirements of this License, to extend the patent
+license to downstream recipients.  "Knowingly relying" means you have
+actual knowledge that, but for the patent license, your conveying the
+covered work in a country, or your recipient's use of the covered work
+in a country, would infringe one or more identifiable patents in that
+country that you have reason to believe are valid.
+
+  If, pursuant to or in connection with a single transaction or
+arrangement, you convey, or propagate by procuring conveyance of, a
+covered work, and grant a patent license to some of the parties
+receiving the covered work authorizing them to use, propagate, modify
+or convey a specific copy of the covered work, then the patent license
+you grant is automatically extended to all recipients of the covered
+work and works based on it.
+
+  A patent license is "discriminatory" if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License.  You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
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+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Use with the GNU Affero General Public License.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU Affero General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
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+but the special requirements of the GNU Affero General Public License,
+section 13, concerning interaction through a network will apply to the
+combination as such.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
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+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
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+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    {{ project }}  Copyright (C) {{ year }}  {{ organization }}
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<http://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..94b0197
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,70 @@
+PIDFILE=/tmp/smtp-sink.pid
+
+help: ## What you're currently reading
+	@IFS=$$'\n' ; \
+	help_lines=(`fgrep -h "##" $(MAKEFILE_LIST) | fgrep -v fgrep | sed -e 's/\\$$//' | sed -e 's/##/:/'`); \
+	clear ; \
+	printf "Usage: make [target]\n\n" ; \
+	printf "%-30s %s\n" "[target]" "help" ; \
+	printf "%-30s %s\n" "--------" "----" ; \
+	for help_line in $${help_lines[@]}; do \
+		IFS=$$':' ; \
+		help_split=($$help_line) ; \
+		help_command=`echo $${help_split[0]} | sed -e 's/^ *//' -e 's/ *$$//'` ; \
+		help_info=`echo $${help_split[2]} | sed -e 's/^ *//' -e 's/ *$$//'` ; \
+		printf '\033[36m'; \
+		printf "%-30s %s" $$help_command ; \
+		printf '\033[0m'; \
+		printf "%s\n" $$help_info; \
+	done; \
+	printf "\n"; \
+
+install: ## Installs dev dependencies
+	composer install
+	npm install
+
+test: server-start ## Runs tests
+	"./vendor/bin/phpunit" --no-coverage
+	make server-stop
+
+coverage: server-start ## Runs tests with code coverage
+	"./vendor/bin/phpunit" --coverage-html=./coverage/ --coverage-clover=./coverage/clover.xml
+	make server-stop
+
+$(PIDFILE): ## Starts the smtp-sink server
+	./node_modules/.bin/smtp-sink -w allowed-sender@example.org & echo $$! > $@
+
+server-start: server-stop $(PIDFILE) ## Stops and starts the smtp-sink server
+
+server-stop: ## Stops smtp-sink server if it's running
+	if [ -e $(PIDFILE) ]; then \
+		PID=$$(cat $(PIDFILE)); \
+		# Getting smtp-sink's pid by matching second column (ppid) of ps output clumsily \
+		NODEPID=$$(ps xao pid,ppid,pgid,sid,comm | awk -v pid="$$PID" '$$2==pid{print $$1}'); \
+		#PGID=$$(ps xao pid,ppid,pgid,sid,comm -p $$PID | sed '1d' | awk '{print $$3}'); \
+		#MYPPID=$$(ps xao pid,ppid,pgid,sid,comm -p $$PID | sed '1d' | awk '{print $$2}'); \
+		echo PID=$$PID; \
+		echo NODEPID=$$NODEPID; \
+		#echo PGID=$$PGID; \
+		#echo PPID=$$PPID; \
+		#echo MYPPID=$$MYPPID; \
+		# Killing nodejs pid that we spawned (hopefully) \
+		if [ ! -z "$$NODEPID" ]; then \
+			kill $$NODEPID || true; \
+		fi; \
+		# Killing juts the PID is not enough sometimes, nodejs server still lingers on (at least on Windows) \
+		if [ ! -z "$$PID" ]; then \
+			kill $$PID || true; \
+		fi; \
+# TODO/FIXME: this manages to kill too much or something, whole recipe fails :/ \
+#		if [ ! -z "$$PGID" ]; then \
+#			kill -- -$$PGID || true; \
+#		fi; \
+		rm -rf $(PIDFILE) || true; \
+	fi; \
+
+clean: ## Removes installed dev dependencies
+	rm -rf ./vendor
+	rm -rf ./node_modules
+
+.PHONY: help install test clean coverage server-start server-stop
diff --git a/README.md b/README.md
index 7d12f32..dc3a9aa 100644
--- a/README.md
+++ b/README.md
@@ -1,57 +1,149 @@
 # SMTP\_Validate\_Email
 
+[![PHP Version](https://img.shields.io/badge/php-5.6%2B-blue.svg?style=flat-square)](https://packagist.org/packages/zytzagoo/smtp-validate-email)
+[![Software License](https://img.shields.io/badge/license-gpl3%2B-brightgreen.svg?style=flat-square)](LICENSE.txt)
+[![Build Status](https://img.shields.io/travis/zytzagoo/smtp-validate-email.svg?style=flat-square)](https://travis-ci.org/zytzagoo/smtp-validate-email)
+[![Scrutinizer Coverage](https://img.shields.io/scrutinizer/coverage/g/zytzagoo/smtp-validate-email.svg?style=flat-square)](https://scrutinizer-ci.com/g/zytzagoo/smtp-validate-email/?branch=master)
+
 Perform email address validation/verification via SMTP.
 
-The class retrieves MX records for the email domain and then connects to the
+The `SMTPValidateEmail\Validator` class retrieves MX records for the email domain and then connects to the
 domain's SMTP server to try figuring out if the address really exists.
 
-### Some features (see the source for more)
+Earlier versions (before 1.0) used the `SMTP_Validate_Email` class name (and did not use namespaces and other now-common PHP features). Care has been taken to keep the old API and migrating old code should be painless. See ["Migrating to 1.0 from older versions"](#migrating-to-1.0-from-older-versions) section. Or just use/download the ancient [0.7 version](https://github.com/zytzagoo/smtp-validate-email/releases/tag/v0.7).
 
-* Not really sending a message, gracefully resetting the session when done
+## Features
+* Not actually sending the message, gracefully resetting the SMTP session when done
 * Command-specific communication timeouts implemented per relevant RFCs
 * Catch-all account detection
 * Batch mode processing supported
-* MX query support on Windows without requiring any PEAR packages
-* Logging and debugging support
+* Logging/debugging support
+* No external dependencies
+* Covered with unit/functional tests
+
+## Installation
+
+Install via [composer](https://getcomposer.org/):
+
+`composer require zytzagoo/smtp-validate-email --update-no-dev`
+
+## Usage examples
 
 ### Basic example
 ```php
-<?php
+require 'vendor/autoload.php';
+
+use SMTPValidateEmail\Validator as SmtpEmailValidator;
+
+/**
+ * Simple example
+ */
+$email     = 'someone@example.org';
+$sender    = 'sender@example.org';
+$validator = new SmtpEmailValidator($email, $sender);
+
+// If debug mode is turned on, logged data is printed as it happens:
+// $validator->debug = true;
+$results   = $validator->validate();
+
+var_dump($results);
+
+// Get log data (log data is always collected)
+$log = $validator->getLog();
+var_dump($log);
+```
+
+### Multiple recipients and other details
+
+```php
+require 'vendor/autoload.php';
+
+use SMTPValidateEmail\Validator as SmtpEmailValidator;
 
-require('smtp-validate-email.php');
+/**
+ * Validating multiple addresses/recipients at once:
+ * (checking multiple addresses belonging to the same server
+ * uses a single connection)
+ */
+$emails    = [
+    'someone@example.org',
+    'someone.else@example.com'
+];
+$sender    = 'sender@example.org';
+$validator = new SmtpEmailValidator($email, $sender):
+$results   = $validator->validate();
 
-$from = 'a-happy-camper@campspot.net'; // for SMTP FROM:<> command
-$email = 'someone@somewhere.net';
+var_dump($results);
 
-$validator = new SMTP_Validate_Email($email, $from);
-$smtp_results = $validator->validate();
+/**
+ * The `validate()` method accepts the same parameters
+ * as the constructor, so this is equivalent to the above:
+ */
+$emails    = [
+    'someone@example.org',
+    'someone.else@example.com'
+];
+$sender    = 'sender@example.org';
+$validator = new SmtpEmailValidator():
+$results   = $validator->validate($emails, $sender);
 
-var_dump($smtp_results);
+var_dump($results);
 ```
 
-### Array usage
-The class supports passing an array of addresses in the constructor or to the
-`validate()` method. Checking multiple addresses on the same server uses
-a single connection.
+## Migrating to 1.0 from older versions
+
+Earlier versions used the global `SMTP_Validate_Email` classname.
+You can keep using that name in your existing code and still switch to the newer (composer-powered) version by using [aliasing/importing](http://php.net/manual/en/language.namespaces.importing.php) like this:
+
+Require the composer package:
+
+`composer require zytzagoo/smtp-validate-email --update-no-dev`
+
+And then in your code:
+
 ```php
-<?php
+require 'vendor/autoload.php';
+
+use SMTPValidateEmail\Validator as SMTP_Validate_Email;
 
-require('smtp-validate-email.php');
+// Now any old code referencing `SMTP_Validate_Email` should still work as it did earlier
+```
 
-$from = 'a-happy-camper@campspot.net'; // for SMTP FROM:<> command
-$emails = array(
-    'someone@somewhere.net',
-    'some-other@somewhere-else.net',
-    'someone@example.com',
-    'someone-else@example.com'
-);
+## Development & Contributions
+See the [Makefile](Makefile) and the development dependencies in [composer.json](composer.json) and [package.json](package.json).
 
-$validator = new SMTP_Validate_Email($emails, $from);
-$smtp_results = $validator->validate();
+Running `make` once you clone (or download) the repository gives you:
 
-// or passing to the validate() method
-// $validator = new SMTP_Validate_Email();
-// $smtp_results = $validator->validate($emails, $from);
+```
+Usage: make [target]
 
-var_dump($smtp_results);
+[target]                       help
+--------                       ----
+help                           What you're currently reading
+install                        Installs dev dependencies
+test                           Runs tests
+coverage                       Runs tests with code coverage
+$(PIDFILE)                     Starts the smtp-sink server
+server-start                   Stops and starts the smtp-sink server
+server-stop                    Stops smtp-sink server if it's running
+clean                          Removes installed dev dependencies
 ```
+
+So, run `make install` to get started. Afterwards you should be able to run the tests.
+
+Tests are powered by `phpunit` and a local `smtp-sink` instance running on port 1025.
+If `smtp-sink` is unavailable, tests requiring it are marked as skipped.
+
+Pull requests are welcome!
+
+In order to get your pull-request merged,
+please follow these simple rules:
+
+* all code submissions must pass cleanly (no errors) with `make test`
+* stick to existing code style (`phpcs` is used)
+* there should be no external dependencies
+* if you want to add significant features/dependencies, file an issue about it first so we can discuss whether the addition makes sense for the project
+
+## [Changelog](CHANGELOG.md)
+
+## [License (GPL-3.0+)](LICENSE.txt)
diff --git a/composer.json b/composer.json
index 7b7fd72..0829dbb 100644
--- a/composer.json
+++ b/composer.json
@@ -22,9 +22,22 @@
         }
     ],
     "require": {
-        "php": ">=5.3.1"
+        "php": ">=5.6"
+    },
+    "require-dev": {
+      "dealerdirect/phpcodesniffer-composer-installer": "^0.4.2",
+      "phpunit/phpunit": "~4.8|~5.1",
+      "squizlabs/php_codesniffer": "^3.0",
+      "wimg/php-compatibility": "^8.0"
     },
     "autoload": {
-        "classmap": ["smtp-validate-email.php"]
+      "psr-4": {
+        "SMTPValidateEmail\\": "src"
+      }
+    },
+    "autoload-dev": {
+      "psr-4": {
+        "SMTPValidateEmail\\Tests\\": "tests"
+      }
     }
 }
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..f8b6b2c
--- /dev/null
+++ b/package.json
@@ -0,0 +1,6 @@
+{
+  "private": true,
+  "devDependencies":{
+    "smtp-sink":"0.0.3"
+  }
+}
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
new file mode 100644
index 0000000..2a5993c
--- /dev/null
+++ b/phpcs.xml.dist
@@ -0,0 +1,109 @@
+<?xml version="1.0"?>
+<ruleset>
+    <arg name="cache" value=".phpcs.cache"/>
+    <file>./src</file>
+    <file>./tests</file>
+    <exclude-pattern>./coverage</exclude-pattern>
+
+    <!-- Show sniff codes in all reports -->
+    <arg value="sp"/>
+
+    <!-- Check for cross-version support for PHP -->
+    <config name="testVersion" value="5.6"/>
+    <rule ref="PHPCompatibility"/>
+
+    <!-- PSR2 + some additions -->
+    <rule ref="PSR2"/>
+
+    <rule ref="Generic.Arrays.DisallowLongArraySyntax"/>
+    <rule ref="Generic.Classes.DuplicateClassName"/>
+    <rule ref="Generic.CodeAnalysis.EmptyStatement"/>
+    <rule ref="Generic.CodeAnalysis.ForLoopShouldBeWhileLoop"/>
+    <rule ref="Generic.CodeAnalysis.ForLoopWithTestFunctionCall"/>
+    <rule ref="Generic.CodeAnalysis.JumbledIncrementer"/>
+    <rule ref="Generic.CodeAnalysis.UnnecessaryFinalModifier"/>
+    <rule ref="Generic.CodeAnalysis.UnusedFunctionParameter"/>
+    <rule ref="Generic.CodeAnalysis.UselessOverridingMethod"/>
+    <rule ref="Generic.ControlStructures.InlineControlStructure"/>
+    <rule ref="Generic.Files.ByteOrderMark"/>
+    <rule ref="Generic.Files.LineEndings"/>
+    <rule ref="Generic.Formatting.DisallowMultipleStatements"/>
+    <rule ref="Generic.Formatting.SpaceAfterCast"/>
+    <rule ref="Generic.Formatting.MultipleStatementAlignment">
+        <properties>
+            <property name="ignoreMultiLine" value="true"/>
+        </properties>
+    </rule>
+    <rule ref="Generic.Functions.CallTimePassByReference"/>
+    <rule ref="Generic.NamingConventions.ConstructorName"/>
+    <rule ref="Generic.NamingConventions.UpperCaseConstantName"/>
+    <rule ref="Generic.PHP.DeprecatedFunctions"/>
+    <rule ref="Generic.PHP.DisallowShortOpenTag"/>
+    <rule ref="Generic.PHP.ForbiddenFunctions"/>
+    <rule ref="Generic.PHP.LowerCaseConstant"/>
+    <rule ref="Generic.PHP.NoSilencedErrors"/>
+    <rule ref="Generic.PHP.Syntax"/>
+    <rule ref="Generic.Strings.UnnecessaryStringConcat"/>
+    <rule ref="Generic.WhiteSpace.DisallowTabIndent"/>
+    <rule ref="Generic.WhiteSpace.ScopeIndent">
+        <properties>
+            <property name="exact" value="false"/>
+        </properties>
+    </rule>
+    <rule ref="PEAR.WhiteSpace.ScopeClosingBrace"/>
+    <rule ref="PEAR.WhiteSpace.ObjectOperatorIndent"/>
+    <rule ref="PEAR.Classes.ClassDeclaration"/>
+    <rule ref="Squiz.Commenting.DocCommentAlignment"/>
+    <rule ref="Squiz.Classes.SelfMemberReference"/>
+    <rule ref="Squiz.Classes.ClassFileName"/>
+    <rule ref="Squiz.Classes.ClassDeclaration"/>
+    <rule ref="Squiz.Commenting.EmptyCatchComment"/>
+    <rule ref="Squiz.Operators.IncrementDecrementUsage"/>
+    <rule ref="Squiz.Functions.MultiLineFunctionDeclaration"/>
+    <rule ref="Squiz.Functions.LowercaseFunctionKeywords"/>
+    <rule ref="Squiz.Functions.FunctionDeclaration"/>
+    <rule ref="Squiz.Functions.FunctionDeclarationArgumentSpacing"/>
+    <rule ref="Squiz.Formatting.OperatorBracket"/>
+    <rule ref="Squiz.PHP.DisallowObEndFlush"/>
+    <rule ref="Squiz.PHP.DisallowSizeFunctionsInLoops"/>
+    <rule ref="Squiz.PHP.DisallowMultipleAssignments"/>
+    <rule ref="Squiz.PHP.DiscouragedFunctions">
+        <severity>0</severity>
+    </rule>
+    <rule ref="Squiz.PHP.EmbeddedPhp"/>
+    <rule ref="Squiz.PHP.Eval"/>
+    <rule ref="Squiz.PHP.ForbiddenFunctions"/>
+    <rule ref="Squiz.PHP.InnerFunctions"/>
+    <rule ref="Squiz.PHP.LowercasePHPFunctions"/>
+    <rule ref="Squiz.PHP.NonExecutableCode"/>
+    <rule ref="Squiz.Scope.MemberVarScope"/>
+    <rule ref="Squiz.Scope.MethodScope"/>
+    <rule ref="Squiz.Scope.StaticThisUsage"/>
+    <rule ref="Squiz.Strings.DoubleQuoteUsage"/>
+    <rule ref="Squiz.WhiteSpace.CastSpacing"/>
+    <rule ref="Squiz.WhiteSpace.ControlStructureSpacing"/>
+    <rule ref="Squiz.WhiteSpace.LanguageConstructSpacing"/>
+    <rule ref="Squiz.WhiteSpace.LogicalOperatorSpacing"/>
+    <rule ref="Squiz.WhiteSpace.MemberVarSpacing"/>
+    <rule ref="Squiz.WhiteSpace.OperatorSpacing"/>
+    <rule ref="Squiz.WhiteSpace.PropertyLabelSpacing"/>
+    <rule ref="Squiz.WhiteSpace.ScopeClosingBrace"/>
+    <rule ref="Squiz.WhiteSpace.ScopeKeywordSpacing"/>
+    <rule ref="Squiz.WhiteSpace.SuperfluousWhitespace">
+        <properties>
+            <property name="ignoreBlankLines" value="true"/>
+        </properties>
+    </rule>
+    <rule ref="Squiz.WhiteSpace.SuperfluousWhitespace.StartFile">
+        <severity>0</severity>
+    </rule>
+    <rule ref="Squiz.WhiteSpace.SuperfluousWhitespace.EndFile">
+        <severity>0</severity>
+    </rule>
+    <rule ref="Squiz.WhiteSpace.SuperfluousWhitespace.EmptyLines">
+        <severity>0</severity>
+    </rule>
+    <rule ref="Squiz.WhiteSpace.SemicolonSpacing"/>
+    <rule ref="Squiz.WhiteSpace.SuperfluousWhitespace"/>
+    <rule ref="Zend.Files.ClosingTag"/>
+</ruleset>
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..1fb775c
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/4.8/phpunit.xsd"
+    backupGlobals="false"
+    backupStaticAttributes="false"
+    bootstrap="vendor/autoload.php"
+    colors="true"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true"
+    processIsolation="false"
+    stopOnFailure="false">
+    <testsuites>
+        <testsuite name="unit">
+            <directory suffix="Test.php">tests/Unit</directory>
+        </testsuite>
+        <testsuite name="functional">
+            <directory suffix="Test.php">tests/Functional</directory>
+        </testsuite>
+    </testsuites>
+    <filter>
+        <whitelist addUncoveredFilesFromWhitelist="true">
+            <directory suffix=".php">src</directory>
+        </whitelist>
+        <blacklist>
+            <directory suffix=".php">vendor</directory>
+        </blacklist>
+    </filter>
+</phpunit>
diff --git a/smtp-validate-email.php b/smtp-validate-email.php
deleted file mode 100644
index 94df305..0000000
--- a/smtp-validate-email.php
+++ /dev/null
@@ -1,867 +0,0 @@
-<?php
-/**
-* SMTP_Validate_Email - Perform email address verification via SMTP.
-* Copyright (C) 2009 Tomaš Trkulja [zytzagoo] <zyt@zytzagoo.net>
-*
-* This program is free software: you can redistribute it and/or modify
-* it under the terms of the GNU General Public License as published by
-* the Free Software Foundation, either version 3 of the License, or
-* (at your option) any later version.
-*
-* This program is distributed in the hope that it will be useful,
-* but WITHOUT ANY WARRANTY; without even the implied warranty of
-* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-* GNU General Public License for more details.
-*
-* You should have received a copy of the GNU General Public License
-* along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*
-* @version 0.7
-* @todo
-*   - finish the graylisting thingy
-*   - perhaps re-implement some methods as static?
-*   - introduce a main socket loop if this state-based approach doesn't work out
-*   - implement TLS probably
-*   - more code examples, more tests
-*
-* The class retrieves MX records for the email domain and then connects to the
-* domain's SMTP server to try figuring out if the address is really valid.
-*
-* Some ideas taken from: http://code.google.com/p/php-smtp-email-validation
-* See the source and comments for more details.
-*/
-
-// Exceptions we throw
-class SMTP_Validate_Email_Exception extends Exception {}
-class SMTP_Validate_Email_Exception_Timeout extends SMTP_Validate_Email_Exception {}
-class SMTP_Validate_Email_Exception_Unexpected_Response extends SMTP_Validate_Email_Exception {}
-class SMTP_Validate_Email_Exception_No_Response extends SMTP_Validate_Email_Exception {}
-class SMTP_Validate_Email_Exception_No_Connection extends SMTP_Validate_Email_Exception {}
-class SMTP_Validate_Email_Exception_No_Helo extends SMTP_Validate_Email_Exception {}
-class SMTP_Validate_Email_Exception_No_Mail_From extends SMTP_Validate_Email_Exception {}
-class SMTP_Validate_Email_Exception_No_Timeout extends SMTP_Validate_Email_Exception {}
-class SMTP_Validate_Email_Exception_No_TLS extends SMTP_Validate_Email_Exception {}
-class SMTP_Validate_Email_Exception_Send_Failed extends SMTP_Validate_Email_Exception {}
-
-// SMTP validation class
-class SMTP_Validate_Email {
-
-    // holds the socket connection resource
-    private $socket;
-
-    // holds all the domains we'll validate accounts on
-    private $domains;
-
-    private $domains_info = array();
-
-    // connect timeout for each MTA attempted (seconds)
-    private $connect_timeout = 10;
-
-    // default username of sender
-    private $from_user = 'user';
-
-    // default host of sender
-    private $from_domain = 'localhost';
-
-    // the host we're currently connected to
-    private $host = null;
-
-    // holds all the debug info
-    public $log = array();
-
-    // array of validation results
-    private $results = array();
-
-    // states we can be in
-    private $state = array(
-        'helo' => false,
-        'mail' => false,
-        'rcpt' => false
-    );
-
-    // print stuff as it happens or not
-    public $debug = false;
-
-    // default smtp port
-    public $connect_port = 25;
-
-    /**
-    * Are 'catch-all' accounts considered valid or not?
-    * If not, the class checks for a "catch-all" and if it determines the box
-    * has a "catch-all", sets all the emails on that domain as invalid.
-    */
-    public $catchall_is_valid = true;
-    public $catchall_test = false; // Set to true to perform a catchall test
-
-    /**
-    * Being unable to communicate with the remote MTA could mean an address
-    * is invalid, but it might not, depending on your use case, set the
-    * value appropriately.
-    */
-    public $no_comm_is_valid = false;
-
-    /**
-     * Being unable to connect with the remote host could mean a server
-     * configuration issue, but it might not, depending on your use case,
-     * set the value appropriately.
-     */
-    public $no_conn_is_valid = false;
-
-    // do we consider "greylisted" responses as valid or invalid addresses
-    public $greylisted_considered_valid = true;
-
-    /**
-    * If on Windows (or other places that don't have getmxrr()), this is the
-    * nameserver that will be used for MX querying.
-    * Set as empty to use the DNS specified via your current network connection.
-    * @see getmxrr()
-    */
-    // protected $mx_query_ns = 'dns1.t-com.hr';
-    protected $mx_query_ns = '';
-
-    /**
-    * Timeout values for various commands (in seconds) per RFC 2821
-    * @see expect()
-    */
-    protected $command_timeouts = array(
-        'ehlo' => 120,
-        'helo' => 120,
-        'tls'  => 180, // start tls
-        'mail' => 300, // mail from
-        'rcpt' => 300, // rcpt to,
-        'rset' => 30,
-        'quit' => 60,
-        'noop' => 60
-    );
-
-    // some constants
-    const CRLF = "\r\n";
-
-    // some smtp response codes
-    const SMTP_CONNECT_SUCCESS = 220;
-    const SMTP_QUIT_SUCCESS = 221;
-    const SMTP_GENERIC_SUCCESS = 250;
-    const SMTP_USER_NOT_LOCAL = 251;
-    const SMTP_CANNOT_VRFY = 252;
-
-    const SMTP_SERVICE_UNAVAILABLE = 421;
-
-    // 450  Requested mail action not taken: mailbox unavailable (e.g.,
-    // mailbox busy or temporarily blocked for policy reasons)
-    const SMTP_MAIL_ACTION_NOT_TAKEN = 450;
-    // 451  Requested action aborted: local error in processing
-    const SMTP_MAIL_ACTION_ABORTED = 451;
-    // 452  Requested action not taken: insufficient system storage
-    const SMTP_REQUESTED_ACTION_NOT_TAKEN = 452;
-
-    // 500  Syntax error (may be due to a denied command)
-    const SMTP_SYNTAX_ERROR = 500;
-    // 502  Comment not implemented
-    const SMTP_NOT_IMPLEMENTED = 502;
-    // 503  Bad sequence of commands (may be due to a denied command)
-    const SMTP_BAD_SEQUENCE = 503;
-
-    // 550  Requested action not taken: mailbox unavailable (e.g., mailbox
-    // not found, no access, or command rejected for policy reasons)
-    const SMTP_MBOX_UNAVAILABLE = 550;
-
-    // 554  Seen this from hotmail MTAs, in response to RSET :(
-    const SMTP_TRANSACTION_FAILED = 554;
-
-    // list of codes considered as "greylisted"
-    private $greylisted = array(
-        self::SMTP_MAIL_ACTION_NOT_TAKEN,
-        self::SMTP_MAIL_ACTION_ABORTED,
-        self::SMTP_REQUESTED_ACTION_NOT_TAKEN
-    );
-
-    /**
-    * Constructor.
-    * @param $emails array  [optional] Array of emails to validate
-    * @param $sender string [optional] Email address of the sender/validator
-    */
-    function __construct($emails = array(), $sender = '') {
-        if (!empty($emails)) {
-            $this->set_emails($emails);
-        }
-        if (!empty($sender)) {
-            $this->set_sender($sender);
-        }
-    }
-
-    /**
-    * Disconnects from the SMTP server if needed.
-    * @return void
-    */
-    public function __destruct() {
-        $this->disconnect(false);
-    }
-
-    public function accepts_any_recipient($domain) {
-        if (!$this->catchall_test) {
-            return false;
-        }
-        $test = 'catch-all-test-' . time();
-        $accepted = $this->rcpt($test . '@' . $domain);
-        if ($accepted) {
-            // success on a non-existing address is a "catch-all"
-            $this->domains_info[$domain]['catchall'] = true;
-            return true;
-        }
-        // log the case in which we get disconnected
-        // while trying to perform a catchall detect
-        $this->noop();
-        if (!($this->connected())) {
-            $this->debug('Disconnected after trying a non-existing recipient on ' . $domain);
-        }
-        // nb: disconnects are considered as a non-catch-all case this way
-        // this might not be true always
-        return false;
-    }
-
-    /**
-    * Performs validation of specified email addresses.
-    * @param array $emails  Emails to validate (recipient emails)
-    * @param string $sender Sender email address
-    * @return array         List of emails and their results
-    */
-    public function validate($emails = array(), $sender = '') {
-
-        $this->results = array();
-
-        if (!empty($emails)) {
-            $this->set_emails($emails);
-        }
-        if (!empty($sender)) {
-            $this->set_sender($sender);
-        }
-
-        if (!is_array($this->domains) || empty($this->domains)) {
-            return $this->results;
-        }
-
-        // query the MTAs on each domain if we have them
-        foreach ($this->domains as $domain => $users) {
-
-            $mxs = array();
-
-            // query the mx records for the current domain
-            list($hosts, $weights) = $this->mx_query($domain);
-
-            // sort out the MX priorities
-            foreach ($hosts as $k => $host) {
-                $mxs[$host] = $weights[$k];
-            }
-            asort($mxs);
-
-            // add the hostname itself with 0 weight (RFC 2821)
-            $mxs[$domain] = 0;
-
-            $this->debug('MX records (' . $domain . '): ' . print_r($mxs, true));
-            $this->domains_info[$domain] = array();
-            $this->domains_info[$domain]['users'] = $users;
-            $this->domains_info[$domain]['mxs'] = $mxs;
-
-            // try each host, $_weight unused in the foreach body, but array_keys() doesn't guarantee the order
-            foreach ($mxs as $host => $_weight) {
-                // try connecting to the remote host
-                try {
-                    $this->connect($host);
-                    if ($this->connected()) {
-                        break;
-                    }
-                } catch (SMTP_Validate_Email_Exception_No_Connection $e) {
-                    // unable to connect to host, so these addresses are invalid?
-                    $this->debug('Unable to connect. Exception caught: ' . $e->getMessage());
-                    $this->set_domain_results($users, $domain, $this->no_conn_is_valid );
-                }
-            }
-
-            // are we connected?
-            if ($this->connected()) {
-                try {
-                    // say helo, and continue if we can talk
-                    if ($this->helo()) {
-
-                        // try issuing MAIL FROM
-                        if (!($this->mail($this->from_user . '@' . $this->from_domain))) {
-                            // MAIL FROM not accepted, we can't talk
-                            $this->set_domain_results($users, $domain, $this->no_comm_is_valid);
-                        }
-
-                        /**
-                        * if we're still connected, proceed (cause we might get
-                        * disconnected, or banned, or greylisted temporarily etc.)
-                        * see mail() for more
-                        */
-                        if ($this->connected()) {
-
-                            $this->noop();
-
-                            // attempt a catch-all test for the domain (if configured to do so)
-                            $is_catchall_domain = $this->accepts_any_recipient($domain);
-
-                            // if a catchall domain is detected, and we consider
-                            // accounts on such domains as invalid, mark all the
-                            // users as invalid and move on
-                            if ($is_catchall_domain) {
-                                if (!($this->catchall_is_valid)) {
-                                    $this->set_domain_results($users, $domain, $this->catchall_is_valid);
-                                    continue;
-                                }
-                            }
-
-                            // if we're still connected, try issuing rcpts
-                            if ($this->connected()) {
-                                $this->noop();
-                                // rcpt to for each user
-                                foreach ($users as $user) {
-                                    $address = $user . '@' . $domain;
-                                    $this->results[$address] = $this->rcpt($address);
-                                    $this->noop();
-                                }
-                            }
-
-                            // saying buh-bye if we're still connected, cause we're done here
-                            if ($this->connected()) {
-                                // issue a rset for all the things we just made the MTA do
-                                $this->rset();
-                                // kiss it goodbye
-                                $this->disconnect();
-                            }
-
-                        }
-
-                    } else {
-
-                        // we didn't get a good response to helo and should be disconnected already
-                        $this->set_domain_results($users, $domain, $this->no_comm_is_valid);
-
-                    }
-
-                } catch (SMTP_Validate_Email_Exception_Unexpected_Response $e) {
-
-                    // Unexpected responses handled as $this->no_comm_is_valid, that way anyone can
-                    // decide for themselves if such results are considered valid or not
-                    $this->set_domain_results($users, $domain, $this->no_comm_is_valid);
-
-                } catch (SMTP_Validate_Email_Exception_Timeout $e) {
-
-                    // A timeout is a comm failure, so treat the results on that domain
-                    // according to $this->no_comm_is_valid as well
-                    $this->set_domain_results($users, $domain, $this->no_comm_is_valid);
-
-                }
-            }
-
-        }
-
-        return $this->get_results();
-
-    }
-
-    public function get_results($include_domains_info = true) {
-        if ($include_domains_info) {
-            $this->results['domains'] = $this->domains_info;
-        }
-        return $this->results;
-    }
-
-    /**
-    * Helper to set results for all the users on a domain to a specific value
-    * @param array $users   Array of users (usernames)
-    * @param string $domain The domain
-    * @param bool $val      Value to set
-    */
-    private function set_domain_results($users, $domain, $val) {
-        if (!is_array($users)) {
-            $users = (array) $users;
-        }
-        foreach ($users as $user) {
-            $this->results[$user . '@' . $domain] = $val;
-        }
-    }
-
-    /**
-    * Returns true if we're connected to an MTA
-    * @return bool
-    */
-    protected function connected() {
-        return is_resource($this->socket);
-    }
-
-    /**
-    * Tries to connect to the specified host on the pre-configured port.
-    * @param string $host   The host to connect to
-    * @return void
-    * @throws SMTP_Validate_Email_Exception_No_Connection
-    * @throws SMTP_Validate_Email_Exception_No_Timeout
-    */
-    protected function connect($host) {
-        $remote_socket = $host . ':' . $this->connect_port;
-        $errnum = 0;
-        $errstr = '';
-        $this->host = $remote_socket;
-        // open connection
-        $this->debug('Connecting to ' . $this->host);
-        $this->socket = @stream_socket_client(
-            $this->host,
-            $errnum,
-            $errstr,
-            $this->connect_timeout,
-            STREAM_CLIENT_CONNECT,
-            stream_context_create(array())
-        );
-        // connected?
-        if (!$this->connected()) {
-            $this->debug('Connect failed: ' . $errstr . ', error number: ' . $errnum . ', host: ' . $this->host);
-            throw new SMTP_Validate_Email_Exception_No_Connection('Cannot ' .
-            'open a connection to remote host (' . $this->host . ')');
-        }
-        $result = stream_set_timeout($this->socket, $this->connect_timeout);
-        if (!$result) {
-            throw new SMTP_Validate_Email_Exception_No_Timeout('Cannot set timeout');
-        }
-        $this->debug('Connected to ' . $this->host . ' successfully');
-    }
-
-    /**
-    * Disconnects the currently connected MTA.
-    * @param bool $quit Issue QUIT before closing the socket on our end.
-    * @return void
-    */
-    protected function disconnect($quit = true) {
-        if ($quit) {
-            $this->quit();
-        }
-        if ($this->connected()) {
-            $this->debug('Closing socket to ' . $this->host);
-            fclose($this->socket);
-        }
-        $this->host = null;
-        $this->reset_state();
-    }
-
-    /**
-    * Resets internal state flags to defaults
-    */
-    private function reset_state() {
-        $this->state['helo'] = false;
-        $this->state['mail'] = false;
-        $this->state['rcpt'] = false;
-    }
-
-    /**
-    * Sends a HELO/EHLO sequence
-    * @todo Implement TLS
-    * @return bool|null  True if successful, false otherwise
-    */
-    protected function helo() {
-        // don't try if it was already done
-        if ($this->state['helo']) {
-            return null;
-        }
-        try {
-            $this->expect(self::SMTP_CONNECT_SUCCESS, $this->command_timeouts['helo']);
-            $this->ehlo();
-            // session started
-            $this->state['helo'] = true;
-            // are we going for a TLS connection?
-            /*
-            if ($this->tls == true) {
-                // send STARTTLS, wait 3 minutes
-                $this->send('STARTTLS');
-                $this->expect(self::SMTP_CONNECT_SUCCESS, $this->command_timeouts['tls']);
-                $result = stream_socket_enable_crypto($this->socket, true,
-                    STREAM_CRYPTO_METHOD_TLS_CLIENT);
-                if (!$result) {
-                    throw new SMTP_Validate_Email_Exception_No_TLS('Cannot enable TLS');
-                }
-            }
-            */
-            return true;
-        } catch (SMTP_Validate_Email_Exception_Unexpected_Response $e) {
-            // connected, but recieved an unexpected response, so disconnect
-            $this->debug('Unexpected response after connecting: ' . $e->getMessage());
-            $this->disconnect(false);
-            return false;
-        }
-    }
-
-    /**
-    * Send EHLO or HELO, depending on what's supported by the remote host.
-    * @return void
-    */
-    protected function ehlo() {
-        try {
-            // modern
-            $this->send('EHLO ' . $this->from_domain);
-            $this->expect(self::SMTP_GENERIC_SUCCESS, $this->command_timeouts['ehlo']);
-        } catch (SMTP_Validate_Email_Exception_Unexpected_Response $e) {
-            // legacy
-            $this->send('HELO ' . $this->from_domain);
-            $this->expect(self::SMTP_GENERIC_SUCCESS, $this->command_timeouts['helo']);
-        }
-    }
-
-    /**
-    * Sends a MAIL FROM command to indicate the sender.
-    * @param string $from   The "From:" address
-    * @return bool          If MAIL FROM command was accepted or not
-    * @throws SMTP_Validate_Email_Exception_No_Helo
-    */
-    protected function mail($from) {
-        if (!$this->state['helo']) {
-            throw new SMTP_Validate_Email_Exception_No_Helo('Need HELO before MAIL FROM');
-        }
-        // issue MAIL FROM, 5 minute timeout
-        $this->send('MAIL FROM:<' . $from . '>');
-        try {
-            $this->expect(self::SMTP_GENERIC_SUCCESS, $this->command_timeouts['mail']);
-            // set state flags
-            $this->state['mail'] = true;
-            $this->state['rcpt'] = false;
-            return true;
-        } catch (SMTP_Validate_Email_Exception_Unexpected_Response $e) {
-            // got something unexpected in response to MAIL FROM
-            $this->debug("Unexpected response to MAIL FROM\n:" . $e->getMessage());
-            // hotmail has been known to do this + was closing the connection
-            // forcibly on their end, so we're killing the socket here too
-            $this->disconnect(false);
-            return false;
-        }
-    }
-
-    /**
-    * Sends a RCPT TO command to indicate a recipient.
-    * @param string $to Recipient's email address
-    * @return bool      Is the recipient accepted
-    * @throws SMTP_Validate_Email_Exception_No_Mail_From
-    */
-    protected function rcpt($to) {
-        // need to have issued MAIL FROM first
-        if (!$this->state['mail']) {
-            throw new SMTP_Validate_Email_Exception_No_Mail_From('Need MAIL FROM before RCPT TO');
-        }
-        $is_valid = false;
-        $expected_codes = array(
-            self::SMTP_GENERIC_SUCCESS,
-            self::SMTP_USER_NOT_LOCAL
-        );
-        if ($this->greylisted_considered_valid) {
-            $expected_codes = array_merge($expected_codes, $this->greylisted);
-        }
-        // issue RCPT TO, 5 minute timeout
-        try {
-            $this->send('RCPT TO:<' . $to . '>');
-            // process the response
-            try {
-                $this->expect($expected_codes, $this->command_timeouts['rcpt']);
-                $this->state['rcpt'] = true;
-                $is_valid = true;
-            } catch (SMTP_Validate_Email_Exception_Unexpected_Response $e) {
-                $this->debug('Unexpected response to RCPT TO: ' . $e->getMessage());
-            }
-        } catch (SMTP_Validate_Email_Exception $e) {
-            $this->debug('Sending RCPT TO failed: ' . $e->getMessage());
-        }
-        return $is_valid;
-    }
-
-    /**
-    * Sends a RSET command and resets our internal state.
-    * @return void
-    */
-    protected function rset() {
-        $this->send('RSET');
-        // MS ESMTP doesn't follow RFC according to ZF tracker, see [ZF-1377]
-        $expected = array(
-            self::SMTP_GENERIC_SUCCESS,
-            self::SMTP_CONNECT_SUCCESS,
-            self::SMTP_NOT_IMPLEMENTED,
-            // hotmail returns this o_O
-            self::SMTP_TRANSACTION_FAILED
-        );
-        $this->expect($expected, $this->command_timeouts['rset'], true);
-        $this->state['mail'] = false;
-        $this->state['rcpt'] = false;
-    }
-
-    /**
-    * Sends a QUIT command.
-    * @return void
-    */
-    protected function quit() {
-        // although RFC says QUIT can be issued at any time, we won't
-        if ($this->state['helo']) {
-            $this->send('QUIT');
-            $this->expect(array(self::SMTP_GENERIC_SUCCESS,self::SMTP_QUIT_SUCCESS), $this->command_timeouts['quit'], true);
-        }
-    }
-
-    /**
-    * Sends a NOOP command.
-    * @return void
-    */
-    protected function noop() {
-        $this->send('NOOP');
-        // erg... "SMTP" code fix some bad RFC implementations
-        // Found at least 1 SMTP server replying to NOOP without
-        // any SMTP code.
-        $expected_codes = array(
-            'SMTP',
-            self::SMTP_BAD_SEQUENCE,
-            self::SMTP_NOT_IMPLEMENTED,
-            self::SMTP_GENERIC_SUCCESS,
-            self::SMTP_SYNTAX_ERROR,
-            self::SMTP_CONNECT_SUCCESS
-        );
-        $this->expect($expected_codes, $this->command_timeouts['noop'], true);
-    }
-
-    /**
-    * Sends a command to the remote host.
-    * @param string $cmd    The cmd to send
-    * @return int|bool      Number of bytes written to the stream
-    * @throws SMTP_Validate_Email_Exception_No_Connection
-    * @throws SMTP_Validate_Email_Exception_Send_Failed
-    */
-    protected function send($cmd) {
-        // must be connected
-        if (!$this->connected()) {
-            throw new SMTP_Validate_Email_Exception_No_Connection('No connection');
-        }
-        $this->debug('send>>>: ' . $cmd);
-        // write the cmd to the connection stream
-        $result = fwrite($this->socket, $cmd . self::CRLF);
-        // did the send work?
-        if ($result === false) {
-            throw new SMTP_Validate_Email_Exception_Send_Failed('Send failed ' .
-            'on: ' . $this->host);
-        }
-        return $result;
-    }
-
-    /**
-    * Receives a response line from the remote host.
-    * @param int $timeout Timeout in seconds
-    * @return string
-    * @throws SMTP_Validate_Email_Exception_No_Connection
-    * @throws SMTP_Validate_Email_Exception_Timeout
-    * @throws SMTP_Validate_Email_Exception_No_Response
-    */
-    protected function recv($timeout = null) {
-        if (!$this->connected()) {
-            throw new SMTP_Validate_Email_Exception_No_Connection('No connection');
-        }
-        // timeout specified?
-        if ($timeout !== null) {
-            stream_set_timeout($this->socket, $timeout);
-        }
-        // retrieve response
-        $line = fgets($this->socket, 1024);
-        $this->debug('<<<recv: ' . $line);
-        // have we timed out?
-        $info = stream_get_meta_data($this->socket);
-        if (!empty($info['timed_out'])) {
-            throw new SMTP_Validate_Email_Exception_Timeout('Timed out in recv');
-        }
-        // did we actually receive anything?
-        if ($line === false) {
-            throw new SMTP_Validate_Email_Exception_No_Response('No response in recv');
-        }
-        return $line;
-    }
-
-    /**
-    * Receives lines from the remote host and looks for expected response codes.
-    * @param int|int[] $codes A list of one or more expected response codes
-    * @param int $timeout The timeout for this individual command, if any
-    * @param bool $empty_response_allowed When true, empty responses are allowed
-    * @return string The last text message received
-    * @throws SMTP_Validate_Email_Exception_Unexpected_Response
-    */
-    protected function expect($codes, $timeout = null, $empty_response_allowed = false) {
-        if (!is_array($codes)) {
-            $codes = (array) $codes;
-        }
-        $code = null;
-        $text = '';
-        try {
-
-            $text = $line = $this->recv($timeout);
-            while (preg_match("/^[0-9]+-/", $line)) {
-                $line = $this->recv($timeout);
-                $text .= $line;
-            }
-            sscanf($line, '%d%s', $code, $text);
-            if (($empty_response_allowed === false && ($code === null || !in_array($code, $codes))) || $code == self::SMTP_SERVICE_UNAVAILABLE) {
-                throw new SMTP_Validate_Email_Exception_Unexpected_Response($line);
-            }
-
-        } catch (SMTP_Validate_Email_Exception_No_Response $e) {
-
-            // no response in expect() probably means that the
-            // remote server forcibly closed the connection so
-            // lets clean up on our end as well?
-            $this->debug('No response in expect(): ' . $e->getMessage());
-            $this->disconnect(false);
-
-        }
-        return $text;
-    }
-
-    /**
-    * Parses an email string into respective user and domain parts and
-    * returns those as an array.
-    * @param string $email 'user@domain'
-    * @return array        ['user', 'domain']
-    */
-    protected function parse_email($email) {
-        $parts = explode('@', $email);
-        $domain = array_pop($parts);
-        $user= implode('@', $parts);
-        return array($user, $domain);
-    }
-
-    /**
-    * Sets the email addresses that should be validated.
-    * @param array $emails  Array of emails to validate
-    * @return void
-    */
-    public function set_emails($emails) {
-        if (!is_array($emails)) {
-            $emails = (array) $emails;
-        }
-        $this->domains = array();
-        foreach ($emails as $email) {
-            list($user, $domain) = $this->parse_email($email);
-            if (!isset($this->domains[$domain])) {
-                $this->domains[$domain] = array();
-            }
-            $this->domains[$domain][] = $user;
-        }
-    }
-
-    /**
-    * Sets the email address to use as the sender/validator.
-    * @param string $email
-    * @return void
-    */
-    public function set_sender($email) {
-        $parts = $this->parse_email($email);
-        $this->from_user = $parts[0];
-        $this->from_domain = $parts[1];
-    }
-
-    /**
-    * Queries the DNS server for MX entries of a certain domain.
-    * @param string $domain The domain for which to retrieve MX records
-    * @return array         MX hosts and their weights
-    */
-    protected function mx_query($domain) {
-        $hosts = array();
-        $weight = array();
-        if (function_exists('getmxrr')) {
-            getmxrr($domain, $hosts, $weight);
-        } else {
-            $this->getmxrr($domain, $hosts, $weight);
-        }
-        return array($hosts, $weight);
-    }
-
-    /**
-     * Provides a windows replacement for the getmxrr function.
-     * Params and behaviour is that of the regular getmxrr function.
-     * @see  http://www.php.net/getmxrr
-     * @param string $hostname
-     * @param string[] $mxhosts
-     * @param int[] $mxweights
-     * @return bool|null
-     */
-    protected function getmxrr($hostname, &$mxhosts, &$mxweights) {
-        if (!is_array($mxhosts)) {
-            $mxhosts = array();
-        }
-        if (!is_array($mxweights)) {
-            $mxweights = array();
-        }
-        if (empty($hostname)) {
-            return null;
-        }
-        $cmd = 'nslookup -type=MX ' . escapeshellarg($hostname);
-        if (!empty($this->mx_query_ns)) {
-            $cmd .= ' ' . escapeshellarg($this->mx_query_ns);
-        }
-        exec($cmd, $output);
-        if (empty($output)) {
-            return null;
-        }
-        $i = -1;
-        foreach ($output as $line) {
-            $i++;
-            if (preg_match("/^$hostname\tMX preference = ([0-9]+), mail exchanger = (.+)$/i", $line, $parts)) {
-                $mxweights[$i] = trim($parts[1]);
-                $mxhosts[$i] = trim($parts[2]);
-            }
-            if (preg_match('/responsible mail addr = (.+)$/i', $line, $parts)) {
-                $mxweights[$i] = $i;
-                $mxhosts[$i] = trim($parts[1]);
-            }
-        }
-        return ($i != -1);
-    }
-
-    /**
-    * Debug helper. If run in a CLI env, it just dumps $str on a new line,
-    * else it prints stuff using <pre>.
-    * @param string $str    The debug message
-    * @return void
-    */
-    private function debug($str) {
-        $str = $this->stamp($str);
-        $this->log($str);
-        if ($this->debug == true) {
-            if (PHP_SAPI != 'cli') {
-                $str = '<br/><pre>' . htmlspecialchars($str) . '</pre>';
-            }
-            echo "\n" . $str;
-        }
-    }
-
-    /**
-    * Adds a message to the log array
-    * @param string $msg The message to add
-    */
-    private function log($msg) {
-        $this->log[] = $msg;
-    }
-
-    /**
-     * Prepends the given $msg with the current date and time inside square brackets.
-     *
-     * @param string $msg
-     *
-     * @return string
-     */
-    private function stamp($msg) {
-        $date = \DateTime::createFromFormat('U.u', sprintf('%.f', microtime(true)))->format('Y-m-d\TH:i:s.uO');
-        $line = '[' . $date . '] ' . $msg;
-
-        return $line;
-    }
-
-    /**
-    * Returns the log array
-    */
-    public function get_log() {
-        return $this->log;
-    }
-
-    /**
-    * Truncates the log array
-    */
-    public function clear_log() {
-        $this->log = array();
-    }
-}
diff --git a/src/Exceptions/Exception.php b/src/Exceptions/Exception.php
new file mode 100644
index 0000000..353c76e
--- /dev/null
+++ b/src/Exceptions/Exception.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class Exception extends \Exception
+{
+
+}
diff --git a/src/Exceptions/NoConnection.php b/src/Exceptions/NoConnection.php
new file mode 100644
index 0000000..48c4dee
--- /dev/null
+++ b/src/Exceptions/NoConnection.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class NoConnection extends Exception
+{
+
+}
diff --git a/src/Exceptions/NoHelo.php b/src/Exceptions/NoHelo.php
new file mode 100644
index 0000000..0c1c0b0
--- /dev/null
+++ b/src/Exceptions/NoHelo.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class NoHelo extends Exception
+{
+
+}
diff --git a/src/Exceptions/NoMailFrom.php b/src/Exceptions/NoMailFrom.php
new file mode 100644
index 0000000..a3c7b9c
--- /dev/null
+++ b/src/Exceptions/NoMailFrom.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class NoMailFrom extends Exception
+{
+
+}
diff --git a/src/Exceptions/NoResponse.php b/src/Exceptions/NoResponse.php
new file mode 100644
index 0000000..efa2359
--- /dev/null
+++ b/src/Exceptions/NoResponse.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class NoResponse extends Exception
+{
+
+}
diff --git a/src/Exceptions/NoTLS.php b/src/Exceptions/NoTLS.php
new file mode 100644
index 0000000..67d9610
--- /dev/null
+++ b/src/Exceptions/NoTLS.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class NoTLS extends Exception
+{
+
+}
diff --git a/src/Exceptions/NoTimeout.php b/src/Exceptions/NoTimeout.php
new file mode 100644
index 0000000..5abf828
--- /dev/null
+++ b/src/Exceptions/NoTimeout.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class NoTimeout extends Exception
+{
+
+}
diff --git a/src/Exceptions/SendFailed.php b/src/Exceptions/SendFailed.php
new file mode 100644
index 0000000..2ca9ccd
--- /dev/null
+++ b/src/Exceptions/SendFailed.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class SendFailed extends Exception
+{
+
+}
diff --git a/src/Exceptions/Timeout.php b/src/Exceptions/Timeout.php
new file mode 100644
index 0000000..12f56ec
--- /dev/null
+++ b/src/Exceptions/Timeout.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class Timeout extends Exception
+{
+
+}
diff --git a/src/Exceptions/UnexpectedResponse.php b/src/Exceptions/UnexpectedResponse.php
new file mode 100644
index 0000000..83b8f4a
--- /dev/null
+++ b/src/Exceptions/UnexpectedResponse.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace SMTPValidateEmail\Exceptions;
+
+class UnexpectedResponse extends Exception
+{
+
+}
diff --git a/src/Validator.php b/src/Validator.php
new file mode 100644
index 0000000..14bbd7f
--- /dev/null
+++ b/src/Validator.php
@@ -0,0 +1,1101 @@
+<?php
+
+namespace SMTPValidateEmail;
+
+use \SMTPValidateEmail\Exceptions\Exception as Exception;
+use \SMTPValidateEmail\Exceptions\Timeout as TimeoutException;
+use \SMTPValidateEmail\Exceptions\NoTimeout as NoTimeoutException;
+use \SMTPValidateEmail\Exceptions\NoConnection as NoConnectionException;
+use \SMTPValidateEmail\Exceptions\UnexpectedResponse as UnexpectedResponseException;
+use \SMTPValidateEmail\Exceptions\NoHelo as NoHeloException;
+use \SMTPValidateEmail\Exceptions\NoMailFrom as NoMailFromException;
+use \SMTPValidateEmail\Exceptions\NoResponse as NoResponseException;
+use \SMTPValidateEmail\Exceptions\SendFailed as SendFailedException;
+
+class Validator
+{
+
+    public $log = [];
+
+    /**
+     * Print stuff as it happens or not
+     *
+     * @var bool
+     */
+    public $debug = false;
+
+    /**
+     * Default smtp port to connect to
+     *
+     * @var int
+     */
+    public $connect_port = 25;
+
+    /**
+     * Are "catch-all" accounts considered valid or not?
+     * If not, the class checks for a "catch-all" and if it determines the box
+     * has a "catch-all", sets all the emails on that domain as invalid.
+     *
+     * @var bool
+     */
+    public $catchall_is_valid = true;
+
+    /**
+     * Whether to perform the "catch-all" test or not
+     *
+     * @var bool
+     */
+    public $catchall_test = false; // Set to true to perform a catchall test
+
+    /**
+     * Being unable to communicate with the remote MTA could mean an address
+     * is invalid, but it might not, depending on your use case, set the
+     * value appropriately.
+     *
+     * @var bool
+     */
+    public $no_comm_is_valid = false;
+
+    /**
+     * Being unable to connect with the remote host could mean a server
+     * configuration issue, but it might not, depending on your use case,
+     * set the value appropriately.
+     */
+    public $no_conn_is_valid = false;
+
+    /**
+     * Whether "greylisted" responses are considered as valid or invalid addresses
+     *
+     * @var bool
+     */
+    public $greylisted_considered_valid = true;
+
+    /**
+     * Timeout values for various commands (in seconds) per RFC 2821
+     *
+     * @var array
+     */
+    protected $command_timeouts = [
+        'ehlo' => 120,
+        'helo' => 120,
+        'tls'  => 180, // start tls
+        'mail' => 300, // mail from
+        'rcpt' => 300, // rcpt to,
+        'rset' => 30,
+        'quit' => 60,
+        'noop' => 60
+    ];
+
+    const CRLF = "\r\n";
+
+    // Some smtp response codes
+    const SMTP_CONNECT_SUCCESS = 220;
+    const SMTP_QUIT_SUCCESS    = 221;
+    const SMTP_GENERIC_SUCCESS = 250;
+    const SMTP_USER_NOT_LOCAL  = 251;
+    const SMTP_CANNOT_VRFY     = 252;
+
+    const SMTP_SERVICE_UNAVAILABLE = 421;
+
+    // 450 Requested mail action not taken: mailbox unavailable (e.g.,
+    // mailbox busy or temporarily blocked for policy reasons)
+    const SMTP_MAIL_ACTION_NOT_TAKEN = 450;
+    // 451 Requested action aborted: local error in processing
+    const SMTP_MAIL_ACTION_ABORTED = 451;
+    // 452 Requested action not taken: insufficient system storage
+    const SMTP_REQUESTED_ACTION_NOT_TAKEN = 452;
+
+    // 500 Syntax error (may be due to a denied command)
+    const SMTP_SYNTAX_ERROR = 500;
+    // 502 Comment not implemented
+    const SMTP_NOT_IMPLEMENTED = 502;
+    // 503 Bad sequence of commands (may be due to a denied command)
+    const SMTP_BAD_SEQUENCE = 503;
+
+    // 550 Requested action not taken: mailbox unavailable (e.g., mailbox
+    // not found, no access, or command rejected for policy reasons)
+    const SMTP_MBOX_UNAVAILABLE = 550;
+
+    // 554 Seen this from hotmail MTAs, in response to RSET :(
+    const SMTP_TRANSACTION_FAILED = 554;
+
+    /**
+     * List of response codes considered as "greylisted"
+     *
+     * @var array
+     */
+    private $greylisted = [
+        self::SMTP_MAIL_ACTION_NOT_TAKEN,
+        self::SMTP_MAIL_ACTION_ABORTED,
+        self::SMTP_REQUESTED_ACTION_NOT_TAKEN
+    ];
+
+    /**
+     * Internal states we can be in
+     *
+     * @var array
+     */
+    private $state = [
+        'helo' => false,
+        'mail' => false,
+        'rcpt' => false
+    ];
+
+    /**
+     * Holds the socket connection resource
+     *
+     * @var resource
+     */
+    private $socket;
+
+    /**
+     * Holds all the domains we'll validate accounts on
+     *
+     * @var array
+     */
+    private $domains = [];
+
+    /**
+     * @var array
+     */
+    private $domains_info = [];
+
+    /**
+     * Default connect timeout for each MTA attempted (seconds)
+     *
+     * @var int
+     */
+    private $connect_timeout = 10;
+
+    /**
+     * Default sender username
+     *
+     * @var string
+     */
+    private $from_user = 'user';
+
+    /**
+     * Default sender host
+     *
+     * @var string
+     */
+    private $from_domain = 'localhost';
+
+    /**
+     * The host we're currently connected to
+     *
+     * @var string|null
+     */
+    private $host = null;
+
+    /**
+     * List of validation results
+     *
+     * @var array
+     */
+    private $results = [];
+
+    /**
+     * @param array|string $emails Email(s) to validate
+     * @param string|null $sender Sender's email address
+     */
+    public function __construct($emails = [], $sender = null)
+    {
+        if (!empty($emails)) {
+            $this->setEmails($emails);
+        }
+        if (null !== $sender) {
+            $this->setSender($sender);
+        }
+    }
+
+    /**
+     * Disconnects from the SMTP server if needed to release resources
+     */
+    public function __destruct()
+    {
+        $this->disconnect(false);
+    }
+
+    public function acceptsAnyRecipient($domain)
+    {
+        if (!$this->catchall_test) {
+            return false;
+        }
+
+        $test     = 'catch-all-test-' . time();
+        $accepted = $this->rcpt($test . '@' . $domain);
+        if ($accepted) {
+            // Success on a non-existing address is a "catch-all"
+            $this->domains_info[$domain]['catchall'] = true;
+            return true;
+        }
+
+        // Log when we get disconnected while trying catchall detection
+        $this->noop();
+        if (!$this->connected()) {
+            $this->debug('Disconnected after trying a non-existing recipient on ' . $domain);
+        }
+
+        /**
+         * N.B.:
+         * Disconnects are considered as a non-catch-all case this way, but
+         * that might not always be the case.
+         */
+        return false;
+    }
+
+    /**
+     * Performs validation of specified email addresses.
+     *
+     * @param array|string $emails Emails to validate (or a single one as a string)
+     * @param string|null $sender Sender email address
+     * @return array List of emails and their results
+     */
+    public function validate($emails = [], $sender = null)
+    {
+        $this->results = [];
+
+        if (!empty($emails)) {
+            $this->setEmails($emails);
+        }
+        if (null !== $sender) {
+            $this->setSender($sender);
+        }
+
+        if (!is_array($this->domains) || empty($this->domains)) {
+            return $this->results;
+        }
+
+        // Query the MTAs on each domain if we have them
+        foreach ($this->domains as $domain => $users) {
+            $mxs = [];
+
+            // Query the MX records for the current domain
+            list($hosts, $weights) = $this->mxQuery($domain);
+
+            // Sort out the MX priorities
+            foreach ($hosts as $k => $host) {
+                $mxs[$host] = $weights[$k];
+            }
+            asort($mxs);
+
+            // Add the hostname itself with 0 weight (RFC 2821)
+            $mxs[$domain] = 0;
+
+            $this->debug('MX records (' . $domain . '): ' . print_r($mxs, true));
+            $this->domains_info[$domain]          = [];
+            $this->domains_info[$domain]['users'] = $users;
+            $this->domains_info[$domain]['mxs']   = $mxs;
+
+            // Try each host, $_weight unused in the foreach body, but array_keys() doesn't guarantee the order
+            foreach ($mxs as $host => $_weight) {
+                // try connecting to the remote host
+                try {
+                    $this->connect($host);
+                    if ($this->connected()) {
+                        break;
+                    }
+                } catch (NoConnectionException $e) {
+                    // Unable to connect to host, so these addresses are invalid?
+                    $this->debug('Unable to connect. Exception caught: ' . $e->getMessage());
+                    $this->setDomainResults($users, $domain, $this->no_conn_is_valid);
+                }
+            }
+
+            // Are we connected?
+            if ($this->connected()) {
+                try {
+                    // Say helo, and continue if we can talk
+                    if ($this->helo()) {
+                        // try issuing MAIL FROM
+                        if (!$this->mail($this->from_user . '@' . $this->from_domain)) {
+                            // MAIL FROM not accepted, we can't talk
+                            $this->setDomainResults($users, $domain, $this->no_comm_is_valid);
+                        }
+
+                        /**
+                         * If we're still connected, proceed (cause we might get
+                         * disconnected, or banned, or greylisted temporarily etc.)
+                         * see mail() for more
+                         */
+                        if ($this->connected()) {
+                            $this->noop();
+
+                            // Attempt a catch-all test for the domain (if configured to do so)
+                            $is_catchall_domain = $this->acceptsAnyRecipient($domain);
+
+                            // If a catchall domain is detected, and we consider
+                            // accounts on such domains as invalid, mark all the
+                            // users as invalid and move on
+                            if ($is_catchall_domain) {
+                                if (!$this->catchall_is_valid) {
+                                    $this->setDomainResults($users, $domain, $this->catchall_is_valid);
+                                    continue;
+                                }
+                            }
+
+                            // If we're still connected, try issuing rcpts
+                            if ($this->connected()) {
+                                $this->noop();
+                                // RCPT for each user
+                                foreach ($users as $user) {
+                                    $address                 = $user . '@' . $domain;
+                                    $this->results[$address] = $this->rcpt($address);
+                                    $this->noop();
+                                }
+                            }
+
+                            // Saying bye-bye if we're still connected, cause we're done here
+                            if ($this->connected()) {
+                                // Issue a RSET for all the things we just made the MTA do
+                                $this->rset();
+                                $this->disconnect();
+                            }
+                        }
+                    } else {
+                        // We didn't get a good response to helo and should be disconnected already
+                        $this->setDomainResults($users, $domain, $this->no_comm_is_valid);
+                    }
+                } catch (UnexpectedResponseException $e) {
+                    // Unexpected responses handled as $this->no_comm_is_valid, that way anyone can
+                    // decide for themselves if such results are considered valid or not
+                    $this->setDomainResults($users, $domain, $this->no_comm_is_valid);
+                } catch (TimeoutException $e) {
+                    // A timeout is a comm failure, so treat the results on that domain
+                    // according to $this->no_comm_is_valid as well
+                    $this->setDomainResults($users, $domain, $this->no_comm_is_valid);
+                }
+            }
+        } // outermost foreach
+
+        return $this->getResults();
+    }
+
+    /**
+     * Get validation results
+     *
+     * @param bool $include_domains_info Whether to include extra info in the results
+     *
+     * @return array
+     */
+    public function getResults($include_domains_info = true)
+    {
+        if ($include_domains_info) {
+            $this->results['domains'] = $this->domains_info;
+        } else {
+            unset($this->results['domains']);
+        }
+
+        return $this->results;
+    }
+
+    /**
+     * Helper to set results for all the users on a domain to a specific value
+     *
+     * @param array $users Users (usernames)
+     * @param string $domain The domain for the users/usernames
+     * @param bool $val Value to set
+     *
+     * @return void
+     */
+    private function setDomainResults(array $users, $domain, $val)
+    {
+        foreach ($users as $user) {
+            $this->results[$user . '@' . $domain] = $val;
+        }
+    }
+
+    /**
+     * Returns true if we're connected to an MTA
+     *
+     * @return bool
+     */
+    protected function connected()
+    {
+        return is_resource($this->socket);
+    }
+
+    /**
+     * Tries to connect to the specified host on the pre-configured port.
+     *
+     * @param string $host Host to connect to
+     *
+     * @throws NoConnectionException
+     * @throws NoTimeoutException
+     *
+     * @return void
+     */
+    protected function connect($host)
+    {
+        $remote_socket = $host . ':' . $this->connect_port;
+        $errnum        = 0;
+        $errstr        = '';
+        $this->host    = $remote_socket;
+
+        // Open connection
+        $this->debug('Connecting to ' . $this->host);
+        // @codingStandardsIgnoreLine
+        $this->socket = /** @scrutinizer ignore-unhandled */ @stream_socket_client(
+            $this->host,
+            $errnum,
+            $errstr,
+            $this->connect_timeout,
+            STREAM_CLIENT_CONNECT,
+            stream_context_create([])
+        );
+
+        // Check and throw if not connected
+        if (!$this->connected()) {
+            $this->debug('Connect failed: ' . $errstr . ', error number: ' . $errnum . ', host: ' . $this->host);
+            throw new NoConnectionException('Cannot open a connection to remote host (' . $this->host . ')');
+        }
+
+        $result = stream_set_timeout($this->socket, $this->connect_timeout);
+        if (!$result) {
+            throw new NoTimeoutException('Cannot set timeout');
+        }
+
+        $this->debug('Connected to ' . $this->host . ' successfully');
+    }
+
+    /**
+     * Disconnects the currently connected MTA.
+     *
+     * @param bool $quit Whether to send QUIT command before closing the socket on our end
+     *
+     * @return void
+     */
+    protected function disconnect($quit = true)
+    {
+        if ($quit) {
+            $this->quit();
+        }
+
+        if ($this->connected()) {
+            $this->debug('Closing socket to ' . $this->host);
+            fclose($this->socket);
+        }
+
+        $this->host = null;
+        $this->resetState();
+    }
+
+    /**
+     * Resets internal state flags to defaults
+     *
+     * @return void
+     */
+    private function resetState()
+    {
+        $this->state['helo'] = false;
+        $this->state['mail'] = false;
+        $this->state['rcpt'] = false;
+    }
+
+    /**
+     * Sends a HELO/EHLO sequence.
+     *
+     * @todo Implement TLS
+     *
+     * @return bool|null True if successful, false otherwise. Null if already done.
+     */
+    protected function helo()
+    {
+        // Don't do it if already done
+        if ($this->state['helo']) {
+            return null;
+        }
+
+        $result = false;
+        try {
+            $this->expect(self::SMTP_CONNECT_SUCCESS, $this->command_timeouts['helo']);
+            $this->ehlo();
+
+            // Session started
+            $this->state['helo'] = true;
+
+            // Are we going for a TLS connection?
+            /*
+            if ($this->tls) {
+                // send STARTTLS, wait 3 minutes
+                $this->send('STARTTLS');
+                $this->expect(self::SMTP_CONNECT_SUCCESS, $this->command_timeouts['tls']);
+                $result = stream_socket_enable_crypto($this->socket, true,
+                    STREAM_CRYPTO_METHOD_TLS_CLIENT);
+                if (!$result) {
+                    throw new SMTP_Validate_Email_Exception_No_TLS('Cannot enable TLS');
+                }
+            }
+            */
+
+            $result = true;
+        } catch (UnexpectedResponseException $e) {
+            // Connected, but got an unexpected response, so disconnect
+            $result = false;
+            $this->debug('Unexpected response after connecting: ' . $e->getMessage());
+            $this->disconnect(false);
+        }
+
+        return $result;
+    }
+
+    /**
+     * Sends `EHLO` or `HELO`, depending on what's supported by the remote host.
+     *
+     * @return void
+     */
+    protected function ehlo()
+    {
+        try {
+            // Modern
+            $this->send('EHLO ' . $this->from_domain);
+            $this->expect(self::SMTP_GENERIC_SUCCESS, $this->command_timeouts['ehlo']);
+        } catch (UnexpectedResponseException $e) {
+            // Legacy
+            $this->send('HELO ' . $this->from_domain);
+            $this->expect(self::SMTP_GENERIC_SUCCESS, $this->command_timeouts['helo']);
+        }
+    }
+
+    /**
+     * Sends a `MAIL FROM` command which indicates the sender.
+     *
+     * @param string $from The "From:" address
+     *
+     * @throws NoHeloException
+     *
+     * @return bool Whether the command was accepted or not
+     */
+    protected function mail($from)
+    {
+        if (!$this->state['helo']) {
+            throw new NoHeloException('Need HELO before MAIL FROM');
+        }
+
+        // Issue MAIL FROM, 5 minute timeout
+        $this->send('MAIL FROM:<' . $from . '>');
+
+        try {
+            $this->expect(self::SMTP_GENERIC_SUCCESS, $this->command_timeouts['mail']);
+
+            // Set state flags
+            $this->state['mail'] = true;
+            $this->state['rcpt'] = false;
+
+            $result = true;
+        } catch (UnexpectedResponseException $e) {
+            $result = false;
+
+            // Got something unexpected in response to MAIL FROM
+            $this->debug("Unexpected response to MAIL FROM\n:" . $e->getMessage());
+
+            // Hotmail has been known to do this + was closing the connection
+            // forcibly on their end, so we're killing the socket here too
+            $this->disconnect(false);
+        }
+
+        return $result;
+    }
+
+    /**
+     * Sends a RCPT TO command to indicate a recipient.
+     *
+     * @param string $to Recipient's email address
+     * @throws NoMailFromException
+     *
+     * @return bool Whether the recipient was accepted or not
+     */
+    protected function rcpt($to)
+    {
+        // Need to have issued MAIL FROM first
+        if (!$this->state['mail']) {
+            throw new NoMailFromException('Need MAIL FROM before RCPT TO');
+        }
+
+        $valid          = false;
+        $expected_codes = [
+            self::SMTP_GENERIC_SUCCESS,
+            self::SMTP_USER_NOT_LOCAL
+        ];
+
+        if ($this->greylisted_considered_valid) {
+            $expected_codes = array_merge($expected_codes, $this->greylisted);
+        }
+
+        // Issue RCPT TO, 5 minute timeout
+        try {
+            $this->send('RCPT TO:<' . $to . '>');
+            // Handle response
+            try {
+                $this->expect($expected_codes, $this->command_timeouts['rcpt']);
+                $this->state['rcpt'] = true;
+                $valid               = true;
+            } catch (UnexpectedResponseException $e) {
+                $this->debug('Unexpected response to RCPT TO: ' . $e->getMessage());
+            }
+        } catch (Exception $e) {
+            $this->debug('Sending RCPT TO failed: ' . $e->getMessage());
+        }
+
+        return $valid;
+    }
+
+    /**
+     * Sends a RSET command and resets certain parts of internal state.
+     *
+     * @return void
+     */
+    protected function rset()
+    {
+        $this->send('RSET');
+
+        // MS ESMTP doesn't follow RFC according to ZF tracker, see [ZF-1377]
+        $expected = [
+            self::SMTP_GENERIC_SUCCESS,
+            self::SMTP_CONNECT_SUCCESS,
+            self::SMTP_NOT_IMPLEMENTED,
+            // hotmail returns this o_O
+            self::SMTP_TRANSACTION_FAILED
+        ];
+        $this->expect($expected, $this->command_timeouts['rset'], true);
+        $this->state['mail'] = false;
+        $this->state['rcpt'] = false;
+    }
+
+    /**
+     * Sends a QUIT command.
+     *
+     * @return void
+     */
+    protected function quit()
+    {
+        // Although RFC says QUIT can be issued at any time, we won't
+        if ($this->state['helo']) {
+            $this->send('QUIT');
+            $this->expect(
+                [self::SMTP_GENERIC_SUCCESS,self::SMTP_QUIT_SUCCESS],
+                $this->command_timeouts['quit'],
+                true
+            );
+        }
+    }
+
+    /**
+     * Sends a NOOP command.
+     *
+     * @return void
+     */
+    protected function noop()
+    {
+        $this->send('NOOP');
+
+        /**
+         * The `SMTP` string is here to fix issues with some bad RFC implementations.
+         * Found at least 1 server replying to NOOP without any code.
+         */
+        $expected_codes = [
+            'SMTP',
+            self::SMTP_BAD_SEQUENCE,
+            self::SMTP_NOT_IMPLEMENTED,
+            self::SMTP_GENERIC_SUCCESS,
+            self::SMTP_SYNTAX_ERROR,
+            self::SMTP_CONNECT_SUCCESS
+        ];
+        $this->expect($expected_codes, $this->command_timeouts['noop'], true);
+    }
+
+    /**
+     * Sends a command to the remote host.
+     *
+     * @param string $cmd The command to send
+     *
+     * @return int|bool Number of bytes written to the stream
+     * @throws NoConnectionException
+     * @throws SendFailedException
+     */
+    protected function send($cmd)
+    {
+        // Must be connected
+        $this->throwIfNotConnected();
+
+        $this->debug('send>>>: ' . $cmd);
+        // Write the cmd to the connection stream
+        $result = fwrite($this->socket, $cmd . self::CRLF);
+
+        // Did it work?
+        if (false === $result) {
+            throw new SendFailedException('Send failed on: ' . $this->host);
+        }
+
+        return $result;
+    }
+
+    /**
+     * Receives a response line from the remote host.
+     *
+     * @param int $timeout Timeout in seconds
+     *
+     * @return string
+     *
+     * @throws NoConnectionException
+     * @throws TimeoutException
+     * @throws NoResponseException
+     */
+    protected function recv($timeout = null)
+    {
+        // Must be connected
+        $this->throwIfNotConnected();
+
+        // Has a custom timeout been specified?
+        if (null !== $timeout) {
+            stream_set_timeout($this->socket, $timeout);
+        }
+
+        // Retrieve response
+        $line = fgets($this->socket, 1024);
+        $this->debug('<<<recv: ' . $line);
+
+        // Have we timed out?
+        $info = stream_get_meta_data($this->socket);
+        if (!empty($info['timed_out'])) {
+            throw new TimeoutException('Timed out in recv');
+        }
+
+        // Did we actually receive anything?
+        if (false === $line) {
+            throw new NoResponseException('No response in recv');
+        }
+
+        return $line;
+    }
+
+    /**
+     * Receives lines from the remote host and looks for expected response codes.
+     *
+     * @param int|int[] $codes List of one or more expected response codes
+     * @param int $timeout The timeout for this individual command, if any
+     * @param bool $empty_response_allowed When true, empty responses are allowed
+     *
+     * @return string The last text message received
+     *
+     * @throws UnexpectedResponseException
+     */
+    protected function expect($codes, $timeout = null, $empty_response_allowed = false)
+    {
+        if (!is_array($codes)) {
+            $codes = (array) $codes;
+        }
+
+        $code = null;
+        $text = '';
+
+        try {
+            $line = $this->recv($timeout);
+            $text = $line;
+            while (preg_match('/^[0-9]+-/', $line)) {
+                $line  = $this->recv($timeout);
+                $text .= $line;
+            }
+            sscanf($line, '%d%s', $code, $text);
+            // TODO/FIXME: This is terrible to read/comprehend
+            if ($code == self::SMTP_SERVICE_UNAVAILABLE ||
+                (false === $empty_response_allowed && (null === $code || !in_array($code, $codes)))) {
+                throw new UnexpectedResponseException($line);
+            }
+        } catch (NoResponseException $e) {
+            /**
+             * No response in expect() probably means that the remote server
+             * forcibly closed the connection so lets clean up on our end as well?
+             */
+            $this->debug('No response in expect(): ' . $e->getMessage());
+            $this->disconnect(false);
+        }
+
+        return $text;
+    }
+
+    /**
+     * Splits the email address string into its respective user and domain parts
+     * and returns those as an array.
+     *
+     * @param string $email Email address
+     *
+     * @return array ['user', 'domain']
+     */
+    protected function splitEmail($email)
+    {
+        $parts  = explode('@', $email);
+        $domain = array_pop($parts);
+        $user   = implode('@', $parts);
+
+        return [$user, $domain];
+    }
+
+    /**
+     * Sets the email addresses that should be validated.
+     *
+     * @param array|string $emails List of email addresses (or a single one a string).
+     *
+     * @return void
+     */
+    public function setEmails($emails)
+    {
+        if (!is_array($emails)) {
+            $emails = (array) $emails;
+        }
+
+        $this->domains = [];
+
+        foreach ($emails as $email) {
+            list($user, $domain) = $this->splitEmail($email);
+            if (!isset($this->domains[$domain])) {
+                $this->domains[$domain] = [];
+            }
+            $this->domains[$domain][] = $user;
+        }
+    }
+
+    /**
+     * Sets the email address to use as the sender/validator.
+     *
+     * @param string $email
+     *
+     * @return void
+     */
+    public function setSender($email)
+    {
+        $parts             = $this->splitEmail($email);
+        $this->from_user   = $parts[0];
+        $this->from_domain = $parts[1];
+    }
+
+    /**
+     * Queries the DNS server for MX entries of a certain domain.
+     *
+     * @param string $domain The domain for which to retrieve MX records
+     * @return array MX hosts and their weights
+     */
+    protected function mxQuery($domain)
+    {
+        $hosts  = [];
+        $weight = [];
+        getmxrr($domain, $hosts, $weight);
+
+        return [$hosts, $weight];
+    }
+
+    /**
+     * Throws if not currently connected.
+     *
+     * @return void
+     * @throws NoConnectionException
+     */
+    private function throwIfNotConnected()
+    {
+        if (!$this->connected()) {
+            throw new NoConnectionException('No connection');
+        }
+    }
+
+    /**
+     * Debug helper. If it detects a CLI env, it just dumps given `$str` on a
+     * new line, otherwise it prints stuff <pre>.
+     *
+     * @param string $str
+     *
+     * @return void
+     */
+    private function debug($str)
+    {
+        $str = $this->stamp($str);
+        $this->log($str);
+        if ($this->debug) {
+            if ('cli' !== PHP_SAPI) {
+                $str = '<br/><pre>' . htmlspecialchars($str) . '</pre>';
+            }
+            echo "\n" . $str;
+        }
+    }
+
+    /**
+     * Adds a message to the log array
+     *
+     * @param string $msg
+     *
+     * @return void
+     */
+    private function log($msg)
+    {
+        $this->log[] = $msg;
+    }
+
+    /**
+     * Prepends the given $msg with the current date and time inside square brackets.
+     *
+     * @param string $msg
+     *
+     * @return string
+     */
+    private function stamp($msg)
+    {
+        $date = \DateTime::createFromFormat('U.u', sprintf('%.f', microtime(true)))->format('Y-m-d\TH:i:s.uO');
+        $line = '[' . $date . '] ' . $msg;
+
+        return $line;
+    }
+
+    /**
+     * Returns the log array
+     *
+     * @return array
+     */
+    public function getLog()
+    {
+        return $this->log;
+    }
+
+    /**
+     * Truncates the log array
+     *
+     * @return void
+     */
+    public function clearLog()
+    {
+        $this->log = [];
+    }
+
+    /**
+     * Compat for old lower_cased method calls.
+     *
+     * @param string $name
+     * @param array  $args
+     *
+     * @return void
+     */
+    public function __call($name, $args)
+    {
+        $camelized = self::camelize($name);
+        if (\method_exists($this, $camelized)) {
+            return \call_user_func_array([$this, $camelized], $args);
+        } else {
+            trigger_error('Fatal error: Call to undefined method ' . self::class . '::' . $name . '()', E_USER_ERROR);
+        }
+    }
+
+    /**
+     * Set the desired connect timeout.
+     *
+     * @param int $timeout Connect timeout in seconds
+     *
+     * @return void
+     */
+    public function setConnectTimeout($timeout)
+    {
+        $this->connect_timeout = (int) $timeout;
+    }
+
+    /**
+     * Get the current connect timeout.
+     *
+     * @return int
+     */
+    public function getConnectTimeout()
+    {
+        return $this->connect_timeout;
+    }
+
+    /**
+     * Set connect port.
+     *
+     * @param int $port
+     *
+     * @return void
+     */
+    public function setConnectPort($port)
+    {
+        $this->connect_port = (int) $port;
+    }
+
+    /**
+     * Get current connect port.
+     *
+     * @return int
+     */
+    public function getConnectPort()
+    {
+        return $this->connect_port;
+    }
+
+    /**
+     * Turn on "catch-all" detection.
+     *
+     * @return void
+     */
+    public function enableCatchAllTest()
+    {
+        $this->catchall_test = true;
+    }
+
+    /**
+     * Turn off "catch-all" detection.
+     *
+     * @return void
+     */
+    public function disableCatchAllTest()
+    {
+        $this->catchall_test = false;
+    }
+
+    /**
+     * Returns whether "catch-all" test is to be performed or not.
+     *
+     * @return bool
+     */
+    public function isCatchAllEnabled()
+    {
+        return $this->catchall_test;
+    }
+
+    /**
+     * Set whether "catch-all" results are considered valid or not.
+     *
+     * @param bool $flag When true, "catch-all" accounts are considered valid
+     *
+     * @return void
+     */
+    public function setCatchAllValidity($flag)
+    {
+        $this->catchall_is_valid = (bool) $flag;
+    }
+
+    /**
+     * Get current state of "catch-all" validity flag.
+     *
+     * @return void
+     */
+    public function getCatchAllValidity()
+    {
+        return $this->catchall_is_valid;
+    }
+
+    /**
+     * Camelizes a string.
+     *
+     * @param string $id A string to camelize
+     *
+     * @return string The camelized string
+     */
+    private static function camelize($id)
+    {
+        return strtr(
+            ucwords(
+                strtr(
+                    $id,
+                    ['_' => ' ', '.' => '_ ', '\\' => '_ ']
+                )
+            ),
+            [' ' => '']
+        );
+    }
+}
diff --git a/tests/Functional/ValidatorTest.php b/tests/Functional/ValidatorTest.php
new file mode 100644
index 0000000..35e2aa2
--- /dev/null
+++ b/tests/Functional/ValidatorTest.php
@@ -0,0 +1,126 @@
+<?php
+
+namespace SMTPValidateEmail\Tests\Functional;
+
+use SMTPValidateEmail\Validator;
+use SMTPValidateEmail\Tests\TestCase;
+use SMTPValidateEmail\Tests\SmtpSinkServerProcess;
+
+/**
+ * Functional tests for Validator class.
+ */
+class ValidatorTest extends TestCase
+{
+    public function testNoConnIsValid()
+    {
+        // Testing no connection, so using a non-existent host on .localhost
+        $uniq    = uniqid();
+        $host    = 'localhost';
+        $email   = 'test@' . $uniq . '.' . $host;
+        $timeout = 1;
+
+        // Default should be false
+        $inst = new Validator($email, 'sender@localhost');
+        $inst->setConnectTimeout($timeout);
+        $this->assertFalse($inst->no_conn_is_valid);
+        $results = $inst->validate();
+        $this->assertFalse($results[$email]);
+
+        $log       = $inst->getLog();
+        $last_line = \array_pop($log);
+        $needle    = 'Unable to connect. Exception caught: Cannot open a connection to remote host';
+        $this->assertContains($needle, $last_line);
+
+        // When changed, it should change the returned result
+        $inst->no_conn_is_valid = true;
+
+        $results = $inst->validate();
+        $this->assertTrue($results[$email]);
+    }
+
+    /**
+     * Requires having node-smtp-sink (`npm install smtp-sink`) locally.
+     * It needs to be ran with -w switch: `smtp-sink -w allowed-sender@example.org`
+     */
+    public function testNoCommIsValidWithLocalSmtpSinkWhitelisted()
+    {
+        // Mark skipped if smtp-sink is not running
+        if (!$this->isSmtpSinkRunning()) {
+            $this->markTestSkipped('smtp-sink is not running.');
+        }
+
+        $email = 'test@localhost';
+
+        $inst = new Validator($email, 'not-allowed@example.org');
+        $inst->setConnectPort(1025);
+        $inst->setConnectTimeout(1);
+        $this->assertFalse($inst->no_comm_is_valid);
+        $results = $inst->validate();
+        $this->assertFalse($results[$email]);
+
+        $inst->no_comm_is_valid = true;
+        $results                = $inst->validate($email, 'not-allowed@example.org');
+        $this->assertTrue($results[$email]);
+    }
+
+    public function testValidSenderWithLocalSmtpSinkWhitelisted()
+    {
+        // Mark skipped if smtp-sink is not running
+        if (!$this->isSmtpSinkRunning()) {
+            $this->markTestSkipped('smtp-sink is not running.');
+        }
+
+        $email = 'test@localhost';
+
+        $inst = new Validator($email, 'allowed-sender@example.org');
+        $inst->setConnectTimeout(1);
+        $inst->setConnectPort(1025);
+        $results = $inst->validate();
+
+        $this->assertTrue($results[$email]);
+    }
+
+    public function testCatchAllConsideredValid()
+    {
+        // Mark skipped if smtp-sink is not running
+        if (!$this->isSmtpSinkRunning()) {
+            $this->markTestSkipped('smtp-sink is not running.');
+        }
+
+        $emails = [
+            'user@localhost',
+            'tester@localhost'
+        ];
+
+        $inst = new Validator($emails, 'allowed-sender@example.org');
+        $inst->setConnectTimeout(1);
+        $inst->setConnectPort(1025);
+        $inst->enableCatchAllTest();
+
+        $results = $inst->validate();
+        foreach ($emails as $email) {
+            $this->assertTrue($results[$email]);
+        }
+    }
+
+    public function testCatchAllConsideredInvalid()
+    {
+        // Mark skipped if smtp-sink is not running
+        if (!$this->isSmtpSinkRunning()) {
+            $this->markTestSkipped('smtp-sink is not running.');
+        }
+
+        $email = 'test@localhost';
+
+        $inst = new Validator($email, 'allowed-sender@example.org');
+        $inst->setConnectTimeout(1);
+        $inst->setConnectPort(1025);
+        $inst->enableCatchAllTest();
+
+        // If a catch-all is detected, the results are not considered valid
+        $inst->setCatchAllValidity(false);
+
+        $results = $inst->validate();
+        $this->assertFalse($results[$email]);
+    }
+}
diff --git a/tests/TestCase.php b/tests/TestCase.php
new file mode 100644
index 0000000..a83ee95
--- /dev/null
+++ b/tests/TestCase.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace SMTPValidateEmail\Tests;
+
+/**
+ * Abstract base class for all test case implementations.
+ *
+ * @package ZWF\GoogleFontsOptimizer\Tests
+ */
+abstract class TestCase extends \PHPUnit_Framework_TestCase
+{
+    protected function isSmtpSinkRunning()
+    {
+        $running = false;
+
+        // @codingStandardsIgnoreLine
+        $fp = /** @scrutinizer ignore-unhandled */ @fsockopen('localhost', 1025);
+        if (false !== $fp) {
+            $running = true;
+            fclose($fp);
+        }
+
+        return $running;
+    }
+}
diff --git a/tests/Unit/ValidatorTest.php b/tests/Unit/ValidatorTest.php
new file mode 100644
index 0000000..a0a4de4
--- /dev/null
+++ b/tests/Unit/ValidatorTest.php
@@ -0,0 +1,143 @@
+<?php
+
+namespace SMTPValidateEmail\Tests\Unit;
+
+use \SMTPValidateEmail\Tests\TestCase;
+use \SMTPValidateEmail\Validator;
+
+/**
+ * Test cases for the Validator class.
+ */
+class ValidatorTest extends TestCase
+{
+    /**
+     * Test exceptions exist and are throwable
+     */
+    public function testExceptions()
+    {
+        $ns         = '\\SMTPValidateEmail\\Exceptions';
+        $exceptions = [
+            'Exception',
+            'NoConnection',
+            'NoHelo',
+            'NoMailFrom',
+            'NoResponse',
+            'NoTimeout',
+            'NoTLS',
+            'SendFailed',
+            'Timeout',
+            'UnexpectedResponse'
+        ];
+        foreach ($exceptions as $name) {
+            $fqcn = $ns . '\\' . $name;
+            $this->expectException($fqcn);
+            $exc = new $fqcn();
+            throw $exc;
+        }
+    }
+
+    public function testOldStyleMethods()
+    {
+        $instance = new Validator();
+        $this->assertSame([], $instance->get_log(), 'old get_log() method still works');
+
+        $instance->log[] = 'test';
+        $this->assertContains('test', $instance->log, 'log contains `test`');
+
+        $instance->clear_log();
+        $this->assertSame([], $instance->log, 'log is cleared via old clear_log() method call');
+        $this->assertNotContains('test', $instance->log, '`test` does not exist in log any more');
+
+        // Unknown methods trigger E_USER_ERROR
+        $this->expectException(\PHPUnit_Framework_Error::class);
+        $instance->undefined_method();
+    }
+
+    public function testGetResults()
+    {
+        $inst     = new Validator();
+        $results1 = $inst->get_results(); // test old style method call while at it
+        $results2 = $inst->getResults(false);
+
+        $this->assertArrayHasKey('domains', $results1, '`domains` key is missing.');
+        $this->assertArrayNotHasKey('domains', $results2, '`domains` key present, but it shouldnt be.');
+        $this->assertSame([], $results2, 'getResults() is not empty');
+    }
+
+    public function testSetEmails()
+    {
+        $emails   = [
+            'email@example.org',
+            'some@some-other-example.org'
+        ];
+        $expected = [
+            'example.org' => ['email'],
+            'some-other-example.org' => ['some']
+        ];
+
+        $inst = new Validator($emails);
+        $this->assertAttributeEquals($expected, 'domains', $inst);
+        $inst->setEmails([]);
+        $this->assertAttributeEquals([], 'domains', $inst);
+        $inst->setEmails($emails);
+        $this->assertAttributeEquals($expected, 'domains', $inst);
+
+        // Test setEmails with a single string
+        $inst->setEmails('test@example.org');
+        $this->assertAttributeEquals(['example.org' => ['test']], 'domains', $inst);
+    }
+
+    public function testSetSender()
+    {
+        $inst = new Validator();
+        $this->assertAttributeEquals('user', 'from_user', $inst);
+        $this->assertAttributeEquals('localhost', 'from_domain', $inst);
+
+        $inst = new Validator([], 'email@example.org');
+        $this->assertAttributeEquals('email', 'from_user', $inst);
+        $this->assertAttributeEquals('example.org', 'from_domain', $inst);
+    }
+
+    public function testValidateMethodWithEmptyParams()
+    {
+        $inst = new Validator();
+        $inst->validate();
+        $this->assertAttributeEquals('user', 'from_user', $inst);
+        $this->assertAttributeEquals('localhost', 'from_domain', $inst);
+    }
+
+    public function testSomeSettersGetters()
+    {
+        $inst = new Validator();
+
+        // Defaults
+        $this->assertSame(25, $inst->getConnectPort());
+        $this->assertSame(10, $inst->getConnectTimeout());
+        $this->assertFalse($inst->isCatchAllEnabled());
+        $this->assertTrue($inst->getCatchAllValidity());
+
+        $inst->setConnectPort(1025);
+        $this->assertSame(1025, $inst->getConnectPort());
+
+        $inst->setConnectTimeout(1);
+        $this->assertSame(1, $inst->getConnectTimeout());
+
+        $inst->enableCatchAllTest();
+        $this->assertTrue($inst->isCatchAllEnabled());
+
+        $inst->disableCatchAllTest();
+        $this->assertFalse($inst->isCatchAllEnabled());
+
+        $inst->setCatchAllValidity(false);
+        $this->assertFalse($inst->getCatchAllValidity());
+    }
+
+    public function testDebugPrint()
+    {
+        $inst        = new Validator('test@invalid.localhost', 'sender@localhost');
+        $inst->debug = true;
+        $results     = $inst->validate();
+        $this->expectOutputRegex('/connecting to invalid.localhost:25/i');
+        $this->expectOutputRegex('/unable to connect\. exception caught:/i');
+    }
+}