[Dovecot] dovecot: pipe() failed: Too many open files

[Ralf Hildebrandt]

I'm encountering lots of 
Oct 31 11:14:25 postamt dovecot: pipe() failed: Too many open files
errors around midday ever since the latest upgrade to 1.0.7.

The errors appear in pairs like this one:
Oct 31 11:20:01 postamt dovecot: pipe() failed: Too many open files
Oct 31 11:20:01 postamt dovecot: imap-login: Internal login failure: user=<username>, method=PLAIN, rip=193.175.174.239, lip=141.42.4.250, TLS

What gives?

-- 
Ralf Hildebrandt (Ralf.Hildebrandt at charite.de)             plonk at charite.de
Postfix - Einrichtung, Betrieb und Wartung       Tel. +49 (0)30-450 570-155
http://www.arschkrebs.de
We're using Postfix - it generally seems to take the approach that the
message that arrives is the message that gets delivered, without any
extra bits being added.                             -- Chris Stratford