Dovecot mail_extra_groups setting is often used insecurely

mailextragroups=mail setting is often used insecurely to give Dovecot access to create dotlocks to /var/mail directory. If you don't use mboxes in /var/mail, make sure this setting is cleared. If you do use /var/mail mboxes and Dovecot gives permission errors without it, do one of the following i...