tail -f /var/log/maillog

Apr 24 23:56:49 mail dovecot: Dovecot starting up
Apr 24 23:56:50 mail imap-login: Can't load private key file /usr/share/ssl/private/dovecot.pem: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch
Apr 24 23:56:50 mail imap-login: Can't load private key file /usr/share/ssl/private/dovecot.pem: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch
Apr 24 23:56:50 mail dovecot: Login process died too early - shutting down
Apr 24 23:56:50 mail dovecot: child 2574 (login) returned error 89
Apr 24 23:56:50 mail dovecot: child 2575 (login) returned error 89
Apr 24 23:56:50 mail imap-login: Can't load private key file /usr/share/ssl/private/dovecot.pem: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch
Apr 24 23:56:50 mail pop3-login: Can't load private key file /usr/share/ssl/private/dovecot.pem: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch