qmtp

from The Free On-line Dictionary of Computing (8 July 2008)

Quick Mail Transfer Protocol
QMTP

   <communications> (QMTP) An {SMTP} replacement that works
   better over high {latency} links as it doesn't require as much
   interaction as SMTP.  QMTP listens on port 209 and is used by
   {qmail}.

   (http://cr.yp.to/mail.html)

   (2007-05-25)