What do they do

• Dovecot provides POP3/POP3S, IMAP/IMAPS services.

• Sieve is used to filter mails.

How to debug them

• Enable debug mode in dovecot config file: /etc/dovecot.conf (RHEL/CentOS) or /etc/dovecot/dovecot.conf (Debian/Ubuntu).

mail_debug = yes

• Restart dovecot service to turn on debug mode.

# /etc/init.d/dovecot restart

Log files

You can now start to monitor log files:

• Dovecot log file is /var/log/dovecot.log.

• Sieve log file is /var/log/sieve.log.

References

• [FAQ] How to move mails which marked as SPAM into Junk folder.

• Variables in dovecot config file: Variables