How to enable Dovecot's debug log options

Introduction

On certain occasions enabling debug mode in Dovecot's mail server is necessary to find answers to indexes, authentication, and inbox issues. This how-to provides information on how to enable all of these debug contexts.

Procedure

1. Log in to the server via SSH as root.
2. Open Dovecot's main configuration file, which is located in /etc/dovecot/dovecot.conf, with your favorite text editor.
3. Enable the following settings by uncommenting and configuring the following directives:

   auth_verbose = yes
   auth_verbose_passwords = no
   auth_debug = yes
   auth_debug_passwords = yes
   mail_debug = yes
   verbose_ssl = yes

4. Save the changes.
5. Restart the Dovecot service by executing the following command:

   /scripts/restartsrv_dovecot

Once the above steps have been performed, you will see debug entries in the /var/log/maillog file like these:

Sep 2 12:07:57 cptest.local dovecot: auth: dict(cptest@cptest.local,198.51.100.225): Password mismatch (given password: REDACTED_NOPASS)
Sep 2 12:07:57 cptest.local dovecot: auth: Debug: dict(cptest@cptest.local,198.51.100.225): CRYPT(REDACTED_NOPASS) != 'REDACTED'