POP3Mailgate

Incoming mail (POP3/IMAP) support can be easily achieved with "fetchmail".

Windows users can download fetchmail from the GNUWin32 project

# .fetchmailrc
   poll mail.yourdomain.com proto pop3:
   username rt password ***** mda "/path/to/perl \
   /path/to/rt-mailgate --url http://localhost/ \
   --queue general --action correspond"
   
   

Add to your startup scripts or manually run fetchmail -d 300 as the rt user to run fetchmail as a daemon and check the rt mailbox every 300 seconds.