Why doesn't Dovecot work?
Dovecot always logs an error message if anything goes wrong, so make sure you're looking at the correct log files. Debug messages may be written to a different log file than error messages. See Logging.
Try logging in manually by sending IMAP commands. If you're trying with an IMAP client you can't be sure if the problem is with the client's configuration or Dovecot's configuration. See TestInstallation (or TestPop3Installation).
Are you using an older version than v1.0? RHEL 5 and Debian Etch distribute v1.0.rc15, and there has been a LOT of fixes since then. If you have a problem, see if NEWS file mentions anything related to it. There are also binary packages available for newer versions.
It says password mismatch
If you're using PAM:
Make sure that dovecot-auth is running as root (assuming it's using /etc/shadow).
PAM errors aren't written to Dovecot's own logs. Usually they go to /var/log/auth.log or something similar.
- Unfortunately PAM's error messages aren't always all that helpful in figuring out what exactly the problem is.
Usually the problem is that you don't have a correctly named file in /etc/pam.d/. See PasswordDatabase/PAM
For non-PAM set auth_debug_passwords=yes and look at what it says in the logs. If it's trying to use a wrong password scheme, you can change that. See Authentication/PasswordSchemes
It says Can't load certificate
And the key isn't password protection and you get an error like:
Sep 29 01:33:54 mail dovecot: imap-login: Can't load certificate file /etc/ssl/private/ssl-cert-mail-cacert.pem: error:0906D06C:PEM routines:PEM_read_bio:no start line Sep 29 01:33:54 mail dovecot: child 27252 (login) returned error 89 Sep 29 01:33:54 mail dovecot: imap-login: Can't load certificate file /etc/ssl/private/ssl-cert-mail-cacert.pem: error:0906D06C:PEM routines:PEM_read_bio:no start line Sep 29 01:33:54 mail dovecot: child 27253 (login) returned error 89
You've mixed up the ssl_cert_file and ssl_key_file directives in your config file.