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Sender Domain Restrictions

Limit outbound mail to configured recipient domains per sender

This plugin restricts users to sending emails only to domains explicitly listed in the configuration file, providing per-sender control over outbound recipient domains.

# plugins/restrictsender.js

exports.register = function () {
  const plugin = this;
  plugin.load_restrictsender_ini();
  plugin.register_hook('rcpt', 'restrict_sender');
}

exports.load_restrictsender_ini = function () {
  const plugin = this;
  plugin.cfg = plugin.config.get('restrictsender.ini', function () {
      plugin.load_restrictsender_ini();
    });
}

exports.restrict_sender = function (next, connection, params) {
    const plugin = this;
    var recip = params[0];
    if (connection.relaying || connection.notes.authentication_results ) {
        var check_domain = connection.transaction.mail_from.host;
        const email = connection.transaction.mail_from.address();
        if (!plugin.cfg[email]) {
           return next();
        }
        var recip_host = recip.host.toLowerCase();
        var a_d = Object.keys(plugin.cfg[email]);
        plugin.loginfo("recipint:" + recip_host);
        if ( a_d.includes(recip_host)) {
             return next();
        }
        return next(DENY,"Sorry, you are only allowed to send mails to particular domains. Please contact system adminstrator if you want to send emails to this domain");
   }
   return next();
}

# config/restrictsender.ini

[user@example.com]
gmail.com