Force Dovecot not to log connect/disconnect messages

My /var/log/mail.log gets constantly flooded with Dovecot connect/disconnect messages like this:

Mar 29 18:15:48 summit dovecot: IMAP([email protected]): Disconnected: Logged out bytes=63/2126          
Mar 29 18:15:50 summit dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=4.3.2.1, lip=1.2.3.4, TLS

These are repeated ad infinitum (to the tune of 11MB of logs per day), and they're obscuring the more important authentication failures and Postfix deliveries/receptions. I've checked Dovecot's wiki page for logging, but no option there stops these messages. Is there any configuration variable I can set within dovecot.conf to stop these messages being sent to mail.log?

Clarification: I still want Dovecot to log to mail.log; I just don't want it logging these frivolous connect/disconnect messages.

Solution 1:

If you are using rsyslog or syslog-ng you can filter syslog messages. Here is an example from the rsyslog help:

with a simple statement:

:msg, contains, "imap-login" ~

or with the if-else script language:

if $programname == 'dovecot' then {
   action(type="omfile" file="/var/log/dovecot.log")
   if $msg contains 'imap-login' then
     action(type="omfile" file="/var/log/dovecot-login.log")
   else
     action(type="omfile" file="/var/log/dovecot.log")
}

http://www.rsyslog.com/doc/rsyslog_conf_filter.html