Complete the MailKit Integration document.

docs/en/Emailing.md

@@ -60,6 +60,8 @@ namespace MyProject
 * **from**: You can set this as the first argument to set a sender email address. If not provided, the default sender address is used (see the email settings below).
 * **isBodyHtml**: Indicates whether the email body may contain HTML tags. **Default: true**.
 
+> `IEmailSender` is the suggested way to send emails, since it makes your code provider independent.
+
 #### MailMessage
 
 In addition to primitive parameters, you can pass a **standard `MailMessage` object** ([see](https://docs.microsoft.com/en-us/dotnet/api/system.net.mail.mailmessage)) to the `SendAsync` method to set more options, like adding attachments.
@@ -68,7 +70,7 @@ In addition to primitive parameters, you can pass a **standard `MailMessage` obj
 
 Sending emails is implemented by the standard `SmtpClient` class ([see](https://docs.microsoft.com/en-us/dotnet/api/system.net.mail.smtpclient)) by default. The implementation class is the `SmtpEmailSender`. This class also expose the `ISmtpEmailSender` service (in addition to the `IEmailSender`).
 
-Most of the time you want to directly use the `ISmtpEmailSender` to make your code provider independent. However, if you want to create an `SmtpClient` easily with the same email settings, you can inject the `ISmtpEmailSender` and use its `BuildClientAsync` method to obtain a `SmtpClient` object and send the email yourself.
+Most of the time you want to directly use the `IEmailSender` to make your code provider independent. However, if you want to create an `SmtpClient` object with the same email settings, you can inject the `ISmtpEmailSender` and use its `BuildClientAsync` method to obtain a `SmtpClient` object and send the email yourself.
 
 ## Queueing Emails / Background Jobs
 

docs/en/MailKit.md

@@ -1,3 +1,48 @@
 # MailKit Integration
 
-TODO!
+[MailKit](http://www.mimekit.net/) is a cross-platform, popular open source mail client library for .net. ABP Framework provides an integration package to use the MailKit as the [email sender](Emailing.md).
+
+## Installation
+
+It is suggested to use the [ABP CLI](CLI.md) to install this package. Open a command line window in the folder of the project (.csproj file) and type the following command:
+
+````bash
+abp add-package Volo.Abp.MailKit
+````
+
+If you haven't done it yet, you first need to install the ABP CLI. For other installation options, see [the package description page](https://abp.io/package-detail/Volo.Abp.MailKit).
+
+## Sending Emails
+
+### IEmailSender
+
+[Inject](Dependency-Injection.md) the standard `IEmailSender` into any service and use the `SendAsync` method to send emails. See the [email sending document](Emailing.md) for details.
+
+> `IEmailSender` is the suggested way to send emails even if you use MailKit, since it makes your code provider independent.
+
+### IMailKitSmtpEmailSender
+
+MailKit package also exposes the `IMailKitSmtpEmailSender` service that extends the `IEmailSender` by adding the `BuildClientAsync()` method. This method can be used to obtain a `MailKit.Net.Smtp.SmtpClient` object that can be used to perform MailKit specific operations.
+
+## Configuration
+
+MailKit integration package uses the same settings defined by the email sending system. So, refer to the [email sending document](Emailing.md) for the settings.
+
+In addition to the standard settings, this package defines `AbpMailKitOptions` as a simple [options](Options.md) class. This class defines only one options:
+
+* **SecureSocketOption**: Used to set one of the `SecureSocketOptions`. Default: `null` (uses the defaults).
+
+**Example: Use *SecureSocketOptions.SslOnConnect***
+
+````csharp
+Configure<AbpMailKitOptions>(options =>
+{
+    options.SecureSocketOption = SecureSocketOptions.SslOnConnect;
+});
+````
+
+Refer to the [MailKit documentation](http://www.mimekit.net/) to learn more about this option.
+
+## See Also
+
+* [Email sending](Emailing.md)