$command_mail_restrictions defines who can use command mail. By default user registerd as a poster can use command mail. To enable that anyone can use command mail, set command_mail_restrictions = permit_anyone Anyone can use command mail. command_mail_restrictions = permit_anyone Anyone except system accounts can use command mail. command_mail_restrictions = reject_system_accounts permit_anyone nobody use command mail. command_mail_restrictions = reject There are other methods to disable command mail. See for more details.