Have you solved your problem when you have shifted to Dovecot. ?
Actually, I use dovecot for imap/imaps. then I shall shift pop3 too.
my server's pop3 service sometimes doesn't accept my emailusers'password
and it reasks user and password.
if I reboot the server, the problem is solved.
I had this problem before, it occured when there were more than 50 domains
on a server and the morercpthosts files was used in combination with the
SMTP authentication patch.
There's a patch available to that patch (or at least to patch 0.31 from
patch) that addresses a bug when there's a failed SMTP AUTH attempt. If
client attempts to send mail to a domain which is not listed in rcpthosts,
qmail-smtpd is unable to read morercpthosts.cdb. Instead, it sends "421
unable to read controls (#4.3.0)" and drops the connection. It seems, a
wrong file descriptor is closed when using the morercpthosts cdb file. For
more information: http://tomclegg.net/qmail/#qmail-smtpd-auth (point 6),
the direct link to the patch file is:
I'm not sure this helps. We have since shifted to Dovecot.