> Some process that runs during the night corrects the
> problem, and
> we can use regular email the next day.
>
> Does anybody know what process resets this mail function so
> I can
> run it manually now?
>
What is the error, if any, when you try to telnet to POP3? What does it say if you tail -f /var/log/maillog when you try to connect?
telnet server.tld 110
If you don't get OK it's not connecting.
If it does prompt OK then you enter:
USER username
PASS password
STAT
you'll get the number of messages and bytes
See more http://jameser.blogspot.com/2006/06/tip-1-checking-pop3-mail-via-telnet.html
--
Dan Kriwitsky