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+If you have a non-library SendGrid issue, please contact our [support team](https://support.sendgrid.com).
+
+If you can't find a solution below, please open an [issue](https://github.com/sendgrid/sendgrid-csharp/issues).
+
+
+## Table of Contents
+
+* [Migrating from v2 to v3](#migrating)
+* [Continue Using v2](#v2)
+* [Testing v3 /mail/send Calls Directly](#testing)
+* [Error Messages](#error)
+* [Versions](#versions)
+* [Environment Variables and Your SendGrid API Key](#environment)
+* [Using the Package Manager](#package-manager)
+
+<a name="migrating"></a>
+## Migrating from v2 to v3
+
+Please review [our guide](https://sendgrid.com/docs/Classroom/Send/v3_Mail_Send/how_to_migrate_from_v2_to_v3_mail_send.html) on how to migrate from v2 to v3.
+
+<a name="v2"></a>
+## Continue Using v2
+
+[Here](https://github.com/sendgrid/sendgrid-csharp/tree/b27983a8f3d84a9d28972f2720cca0315ad9fe32) is the last working version with v2 support.
+
+Using Nuget:
+
+```bash
+PM> Install-Package Sendgrid -Version 6.3.4
+```
+
+Download:
+
+Click the "Clone or download" green button in [GitHub](https://github.com/sendgrid/sendgrid-csharp/tree/b27983a8f3d84a9d28972f2720cca0315ad9fe32) and choose download.
+
+<a name="testing"></a>
+## Testing v3 /mail/send Calls Directly
+
+[Here](https://sendgrid.com/docs/Classroom/Send/v3_Mail_Send/curl_examples.html) are some cURL examples for common use cases.
+
+<a name="error"></a>
+## Error Messages
+
+To read the error message returned by SendGrid's API:
+
+```csharp
+dynamic response = await sg.client.mail.send.post(requestBody: mail.Get());
+Console.WriteLine(response.StatusCode);
+Console.WriteLine(response.Body.ReadAsStringAsync().Result);
+Console.WriteLine(response.Headers.ToString());
+```
+
+<a name="versions"></a>
+## Versions
+
+We follow the MAJOR.MINOR.PATCH versioning scheme as described by [SemVer.org](http://semver.org). Therefore, we recommend that you always pin (or vendor) the particular version you are working with to your code and never auto-update to the latest version. Especially when there is a MAJOR point release, since that is guarenteed to be a breaking change. Changes are documented in the [CHANGELOG](https://github.com/sendgrid/sendgrid-csharp/blob/master/CHANGELOG.md) and [releases](https://github.com/sendgrid/sendgrid-csharp/releases) section.
+
+<a name="environment"></a>
+## Environment Variables and Your SendGrid API Key
+
+All of our examples assume you are using [environment variables](https://github.com/sendgrid/sendgrid-csharp#setup-environment-variables) to hold your SendGrid API key.
+
+If you choose to add your SendGrid API key directly (not recommended):
+
+`string apiKey = Environment.GetEnvironmentVariable("SENDGRID_API_KEY", EnvironmentVariableTarget.User);`
+
+becomes
+
+`string apiKey = "SENDGRID_API_KEY";`
+
+In the first case SENDGRID_API_KEY is in reference to the name of the environment variable, while the second case references the actual SendGrid API Key.
+
+<a name="package-manager"></a>
+## Using the Package Manager
+
+We upload this library to [Nuget](https://www.nuget.org/packages/SendGrid) whenever we make a release. This allows you to use [Nuget](https://www.nuget.org) for easy installation.
+
+In most cases we recommend you download the latest version of the library, but if you need a different version, please use:
+
+`PM> Install-Package Sendgrid -Version X.X.X`