POP3 and IMAP stop respond

[thavaht]

I have Postfix + Courier-POP3/Courier-IMAP configured on Debian etch.
From times to times POP3 and IMAP stop working.
This is the case now that when I try to use POP3 I get the following alert: “Connection to mail… timed out” or “Your POP3 server does not respond…”
When using IMAP I get the following: “Login to server failed …”

The system was working normally two days ago and no changes where made in configurations.
Could someone help getting out from this?
Thanks.

[falko]

Any errors in your mail log?
Do you still see them in the output of netstat -tap when this happens?

You could install monit to watch and restart Courier: http://www.howtoforge.com/server_monitoring_with_munin_monit_debian_etch_p2

[thavaht]

I found it was a DNS conflict and probably it was the same reason every time the error occurred. Anyway I believe it will be useful to install monit. Thank you for helping.