How to Configure Postfix for Specific Domain Mail Delivery

postfix

We currently have postfix handling emails generated by a number of apps. A number of these emails are destined for users inside the organisation, whose mail is on an Exchange server in the same site as the postfix box.

I'm looking for a way to do this, but my Google-fu is letting me down:

If the recipient domain is one of our domains, deliver the mail to host mail.example.com. All other mail is delivered by looking up the MX record/s and processing normally.

Edit: to clarify, the apps generating the emails are sending to users outside of our organisation too, postfix is not receiving mail at all.

Best Answer

Instructions work for Ubuntu, you may need to adjust for other distros.

Add the following to /etc/postfix/main.cf:

relay_domains = domain1.com, domain2.com
transport_maps = hash:/etc/postfix/transport
relay_recipient_maps = hash:/etc/postfix/relay_recipients
relay_transport = relay

Create the file /etc/postfix/transport:

domain1.com  smtp:[mail.example.com]
domain2.com  smtp:[mail.example.com]

Create the file /etc/postfix/relay_recipients:

@domain1.com x
@domain2.com x

Run these commands:

$ sudo postmap /etc/postfix/transport
$ sudo postmap /etc/postfix/relay_recipients
$ sudo /etc/init.d/postfix reload

Related Solutions

How to configure postfix to send local mail to another local server

I'd do it earlier still - by removing your domain name from mydestination, mail for that domain should be delivered to the server listed as MX for your domain. If you want to specify a server, as opposed to using the MX, you should use the file /path/to/postfix/etc/transport for this. That file should then look like this:

# all mails to our own domain should go to our main incoming server
ourdomain.com    smtp:[mainserver.ourdomain.com]

Please note that the [] marks are important - without them, your server will still lookup the MX record for mainserver.ourdomain.com.

After editing the file, use the command postmap /path/to/postfix/etc/transport

You also need to make sure that postfix knows to use that file, by editing /path/to/postfix/etc/main.cf with the following line:

transport_maps = hash:/path/to/postfix/etc/transport

if your system uses db files. If instead it uses dbm files, the line should be

transport_maps = dbm:/path/to/postfix/etc/transport

Postfix: mail delivered locally, but I wanted relayhost delivery

Gah! Yes, you're right, Ismooth - I hadn't realized the difference between the to and orig_to line was coming from Postfix, not the upstream mail host. In this case, the standard distribution of Postfix loaded onto our server by the company contained the line:

masquerade_domains = example.net

which of course stripped off the "tardis" bit and turned george@tardis.example.net into george@example.net.

The solution was to remove that line, then remove $mydomain from the mydestination directive. Problem solved. Thanks for the help!

Best Answer

Related Solutions

How to configure postfix to send local mail to another local server

Postfix: mail delivered locally, but I wanted relayhost delivery

Related Topic