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Old 03-18-2004, 11:34 AM   #1
Registered: Oct 2003
Location: MN
Distribution: CentOS, Fedora
Posts: 182

Rep: Reputation: 30
Postfix sending mail for unknown users to other server?

Hey all,

I have a Postfix/Squirrelmail mail server set up running as a test box right now. It will be replacing our primary mail server (running Novell) in the near future, but we wanted to do some testing and trial runs before moving everyone over to it. So, what I'm looking for a way to do is to move only some people over to it while leaving the bulk of the users on the old system. However.. I'm not sure how to do this.

Mail for our domain comes into a Viruswall box, which scans all incoming messages for viruses and SPAM, then forwards it to an internal IP that the current mail server is running on. So it would be easy enough to set up all the users on the Postfix/Squirrelmail box, make a change on the Viruswall box, and have all new mail come in there. But, since I want to try just a handful of users first, I was wondering if there is a way to set up a few users on the new box, and have Postfix forward messages for unknown users to the other server. It kind of sounds like the luser_relay parameter might be able to do it, but since the destination domain would be the same as the mydestination parameter, I'm not sure how to set it up to forward. Can I specify an IP address to forward to somehow for unknown recipients that all messages would be sent to?

Thanks for taking the time to read all this... please just ask if any additional information is needed.
Old 03-18-2004, 01:27 PM   #2
Registered: Sep 2003
Location: Dallas, Tx, USA
Distribution: Red Hat, Gentoo, Libranet
Posts: 98

Rep: Reputation: 16
I'm not a Postfix wizard, so before doing all the work of digging into Postfix parameters, I'm going to suggest what popped to mind as the easy way first.

Rather than redirecting all your mail to the new box and trying to write a "everybody but these" rule for redirection, leave it pointed to the old box, and just put entries for each userid you want on the postfix box in /etc/aliases.

For instance, say I'm one of the guys you want on the Postfix box. For the example, the current mail server is and the Postfix box is

In the /etc/aliases file on prodmail, put an entry that says:


(You might be able to abreviate that to just clacour@testmail, if your name resolution is set up the right way.)

All of my mail will now hit the old server first, get rerouted to testmail, and be processes like normal there. When you're satisfied that everything on testmail works the way you want it to, then you redirect the output of the Viruswall box to the Postfix box, which is now your new production mail server.

Hope this helps,

Old 03-18-2004, 01:33 PM   #3
Registered: Oct 2003
Location: MN
Distribution: CentOS, Fedora
Posts: 182

Original Poster
Rep: Reputation: 30

Hmm.. that's a good idea, I'll have to look into it and see if Novell has any options to set things up that way. It would be really easy if both systems were Postfix.. but we have this old Novell box from well before I started here, and I'm not well versed in Novell by any means. I'll look into it though, see if there's a way to do something like that on a per user basis.



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