[CentOS] Mail server, IMAP question

> Dec 11 17:46:54 kines imap(nando at kines.dyndns.org): 
> opendir(/usr/libexec/dovecot/imap) failed: Not a directory

My guess (you haven't provided logs or configuration information) is
that you have a misconfiguration of your mail delivery agent. It looks
like postfix is trying to deliver your mail to a directory that is
actually a file.
I'd troubleshoot that. If you get nowhere with this I would suggest
posting your errors (full logs of the event) and configuration (postconf
-n output) to the postfix mailing list.

alex