FIRST With built-in iCal and vCal Calendaring support

FIRST With built-in vCard Support

FIRST To Let you add DataGrids to your Email Body

FIRST To Let you Email UserControls

FIRST To Create attachments from Streams

FIRST To Create attachments from URLs

FIRST To Embed Images from HTML Strings

FIRST To Create Embedded Images from Byte Arrays

FIRST To Automatically process ASP.NET Exceptions

FIRST To Automatically process ASP.NET Web Forms

FIRST To Email from the web.config Settings

FIRST To Embed Images from a URL

FIRST To MailMerge a DataTable

FIRST To MailMerge a DataReader

FIRST To MailMerge a DataSet

FIRST to natively support IMail's spool file format

FIRST to natively support Microsoft's SMTP file format

FIRST to support these methods asynchronously

FIRST to email web pages and embed the images

FIRST to support the Outlook Sensitivity

FIRST to support the Outlook Confidentiality

FIRST to remove <script> blocks from emailed web pages.

Want more? Check out the complete feature list here.