[Dovecot] dovecot died

[Marten Lehmann]

Hello,

today our dovecot imap server died. The following message appeared in 
the logfile:

dovecot: Mar 23 07:00:58 Error: pipe() failed: Too many open files

We have one dovecot instance for pop3 and one for imap, so while the 
pop3-service was still available, the imap-service was not running any more.

I've seen a lots of users keeping there imap-connections idle for hours, 
often more than one per mailbox. How can I limit this? Can I limit the 
maximum time a connection can be open?

Regards
Marten