Connected_to_hhh.ttt.yyy.xxx_but_connection_died._Possible_duplicate

qmail-remote connected to another server and sent the message, but the connection died before qmail-remote received confirmation of receipt. qmail therefore has to try again (later) to deliver the message, which /might/result in the recipient receiving two copies of the message, /if/ the first attempt actually was successful (which qmail has no way of knowing).

It is possible that the remote SMTP server is in a state that can't produce the acknowledgment due to some internal problem. It is also possible that another appliance creates this problem. Broken versions of PIX firewalls, with 'fixup smtp' enabled, require <CR><LF>.<CR><LF> to be all in the same packet. If PIX is a possibility is easy to verify by a simple 'telnet hhh.ttt.yyy.xxx 25'. If you getgreeted with a (*) obfuscated greeting this most probably is a PIX problem.

This error is also seen from remote hosts that are under heavy load. Hotmail is known to do this, so are many of the off site mail scan services.