I’m trying to figure out a problem I’m having with a few email accounts from one client (so far only one has complained, but there could be more).
During some periods of the day when the demand on the server increases he gets an authentication error from Dovecot while trying to connect via IMAP.
I enabled debug logging on Dovecot and don’t see anything strange. The errors are logged as "password mismatch", but the user didn’t change his password and if he disconnects one of his devices (such as his phone), he stops getting the error. So everything points out to something like Dovecot reaching a limit for IMAP connections.
If that’s the case: why is it showing a password error? and is it possible to increase that limit?
I’ve seen this very old thread on Dovecot’s mailing list, but it doesn’t seem to be related since its about a much older Dovecot version on a very different operating system.
I’m running Dovecot 2.1.9 on a CentOS 5.7 (x86_84).
Any ideas? Has this happened to you before?