Mail::MtPolicyd::Plugin::SMTPVerify - mtpolicyd plugin for remote SMTP address checks

       Markus Benning <ich@markusbenning.de>

Parameters
       The module takes the following parameters:

       (uc_)enabled (default: on)
           Enable/disable this check.

       host (default: empty)
           If defined this host will be used for checks instead of a MX.

       port (default: 25)
           Port to use for connection.

       check_tlsa (default: off)
           Set to 'on' to enable check if an TLSA record for the MX exists.

           This requires that your DNS resolver returns the AD flag for DNSSEC secured records.

       check_openpgp (default: off)
           Set to 'on' to enable check if an OPENPGPKEY records for the recipients exists.

       sender_field (default: recipient)
           Field to take the MAIL FROM address from.

       sender (default: empty)
           If set use this fixed sender in MAIL FROM instead of sender_field.

       recipient_field (default: sender)
           Field to take the RCPT TO address from.

       size_field (default: size)
           Field to take the message SIZE from.

       perm_fail_action (default: empty)
           Action to return if the remote server returned an permanent error for this recipient.

           The string "%MSG%" will be replaced by the smtp message:

             perm_fail_action = "reject %MSG%"

       temp_fail_action (default: empty)
           Like  perm_fail_action but this message is returned when an temporary error is returned by the remote
           smtp server.

             temp_fail_action = "defer %MSG%"

       perm_fail_score (default: empty)
           Score to apply when a permanent error is returned for this recipient.

       temp_fail_score (default: empty)
           Score to apply when a temporary error is returned for this recipient.

       has_starttls_score (default: emtpy)
       no_starttls_score (default: emtpy)
           Score to apply when the smtp server of the recipient announces support for STARTTLS extension.

       has_tlsa_score (default: empty)
       no_tlsa_score (default: empty)
           Score to apply when there is a TLSA or no TLSA record for the remote SMTP server.

       has_openpgp_score (default: empty)
       no_openpgp_score (default: empty)
           Score to apply when a OPENPGPKEY record for the recipient exists or not exists.

       This software is Copyright (c) 2014 by Markus Benning <ich@markusbenning.de>.

       This is free software, licensed under:

         The GNU General Public License, Version 2, June 1991

perl v5.38.2                                       2024-05-26              Mail::MtPolicy...gin::SMTPVerify(3pm)

       This plugin can be used to do remote SMTP verification of addresses.

       To check if the recipient exists on a internal relay and mailbox is able to receive a message of this
       size:

         <Plugin smtp-rcpt-check>
           module = "SMTPVerify"

           host = "mail.company.internal"
           sender_field = "sender"
           recipient_field = "recipient"
           # send SIZE to check quota
           size_field = "size"

           temp_fail_action = "defer %MSG%"
           perm_fail_action = "reject %MSG%"
         </Plugin>

       Do some very strict checks on sender address:

         <Plugin sender-sender-check>
           module = "SMTPVerify"

           # use a verifiable address in MAIL FROM:
           sender = "horst@mydomain.tld"
           recipient_field = "sender"
           no_starttls_action = "reject sender address does not support STARTTLS"
           temp_fail_action = "defer sender address failed verification: %MSG%"
           perm_fail_action = "reject sender address does not accept mail: %MSG%"
         </Plugin>

       Or do advanced checking of sender address and apply a score:

         <Plugin sender-sender-check>
           module = "SMTPVerify"

           # use a verifiable address in MAIL FROM:
           sender = "horst@mydomain.tld"
           recipient_field = "sender"
           check_tlsa = "on"
           check_openpgp = "on"

           temp_fail_score = "1"
           perm_fail_score = "3"

           has_starttls_score = "-1"
           no_starttls_score = "5"
           has_tlsa_score = "-3"
           has_openpgp_score = "-3"
         </Plugin>

       Based on the score you can later apply greylisting or other actions.

       Mail::MtPolicyd::Plugin::SMTPVerify - mtpolicyd plugin for remote SMTP address checks

       version 2.05