Karl O. Pinc:
> What should happen, and what does happen a lot, is that the smtpd side
> eventually receives a QUIT, responds with a 221, and closes the
> connection. (At least I assume that's what's happening.) However,
> sometimes, ps shows that the awk process has finished, is gone and
> does not show, but the nc process is still running, and waiting for
> smtpd to close it's side of the network socket. I can't determine the
> conditions that will cause nc to be left running. In all cases the
> mail is successfully delivered.
>
> Offhand I can't think of a "regular" smtp protocol exchange that shuts
> down the mail sending side of the network socket and leaves the mail
> receiving side wanting to talk with the sending side, although this is
> what seems to be happening. I'm guessing that the postfix smtp side
> sometimes shuts down early, after sending a SMTP QUIT, leaving the
> smtpd side still trying to send the 221 response. I can't think of
> why it would do that, given that postfix is essentially talking to
> itself.
Instead of guessing, run a network sniffer that captures the
packet content.
Wietse
