Downgrade dovecot to 1.0.10 give me error :
mail# /usr/local/etc/rc.d/dovecot start
Starting dovecot.
Error: Error in configuration file /usr/local/etc/dovecot.conf line 262: Unknown setting: mail_privileged_group
Fatal: Invalid configuration in /usr/local/etc/dovecot.conf
Find line 262, talk about mail_priveleged_group
solution :
change
mail_privileged_group = mail
into
mail_extra_groups = mail
and start dovecot service.
Work 🙂