Tag Archive: postfix

I had to solve a problem for a customer where they need to delegate management of backup MX servers to their clients. Of course, they don’t want to give their clients root access to their server, but they can write an app that gives users access to certain entries in a database, based on their privileges. This means I can join my two favourite server apps in the world: Postfix + MySQL

First, we need to create a database and some tables. These are quick and dirty and only meant to be a proof of concept. The fields a pretty straight forward: id is just a number, domain is the domain being relayed, and destination is the primary MX or where ever you need the mail to go. The syntax is as per the Postfix transport documentation. :domain.tld will do an mx lookup on domain.tld, and smtp:host.domain.tld will deliver directly to the host specified. My database is called ‘backupmx’

CREATE TABLE `domains` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `domain` varchar(128) NOT NULL DEFAULT '',
  `destination` varchar(128) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`),
  UNIQUE KEY `domain` (`domain`)

CREATE TABLE `recipients` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `address` varchar(255) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`),
  KEY `address` (`address`)

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I recently needed to do some testing with sending mail, and needed a host that would accept mails without asking questions, and just discard it. This turned out to be pretty easy with Postfix.   Starting with a fresh installation on Debian Lenny, add the following to /etc/postfix/main.cf:

# accept all mail
relay_domains = static:ALL
# then get rid of it
smtpd_end_of_data_restrictions = check_client_access static:discard

And before I even got to send a test mail, someone had beat me to it:

Jul  9 03:43:58 mx02 postfix/smtpd[13940]: 6BC681740FC: discard: END-OF-MESSAGE
from 114-45-59-8.dynamic.hinet.net[]: <114-45-59-8.dynamic.hinet.net
[]>: Client host triggers DISCARD action; from=<z2007tw@yahoo.com.tw>
to=<tv9977ccv@yahoo.com.tw> proto=SMTP helo=<>

Yes, I probably should have firewalled out port 25…