WIP

Protocol restrictions and IP access

Denied access will be shown to the user as failed login attempts.

Protocol restrictions in Dovecot

Protocol restrictions work by filtering the passdb query for IMAP and POP3 as well as reading the JSON value for %s_access where %s reflects the protocol seen by Dovecot.

In the future we may use virtual colums in SQL to add an index on these values.

Protocol restrictions in Postfix

Filtering SMTP protocol access works by using a check_sasl_map in the smtpd_recipient_restrictions.