On Windows Server 2012 the SMTP Server is deprecated, but you can still install it using the Add Roles and Features Wizard in the Server Manager.

Lately we received this error:

System.Net.Mail.SmtpException: Exceeded storage allocation. The server response was: 4.3.1 Session size exceeds fixed maximum session size
   at System.Net.Mail.DataStopCommand.CheckResponse(SmtpStatusCode statusCode, String serverResponse)
   at System.Net.Mail.DataStopCommand.Send(SmtpConnection conn)
   at System.Net.Mail.SmtpConnection.OnClose(Object sender, EventArgs args)
   at System.Net.ClosableStream.Close()
   at System.Net.Mail.MailWriter.Close()
   at System.Net.Mail.SmtpClient.Send(MailMessage message)

It turned out the attachment size was to big for the SMTP Server. You can change these settings the same way as in Windows Server 2012. Use the Windows Server 2012 Search charm to find the IIS 6.0 Manager. On the tab “messages” you can change the Limit message size.