Two Exchange Servers in differnt domains sharing port 25

I'd like to setup a second domain on the same network as my current domain.  What i'd like to know is if it's possible for two exchange 2003 servers to listen on port 25 for mail.  This is a network using a broadband connection so there's no fancy router involved.  Can this be done?  This is just a test environment.

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SembeeConnect With a Mentor Commented:
Easily done with an SMTP Connector.
See my web site here:

Hedley PhillipsOwnerCommented:
Yes and no

If you have each server listening on port 25 with two MX records, then you can desigante which one you want as your primary mail server and which one is your secondary server in the MX records.

Then you just need to NAT incoming over your Firewall to each server.

The problem with this is, if you reboot your primary server or if it is off line for any reason, mail will automatically go to your secondary server and then it is stuck there. You can't have two exchange servers working in a 'cluster' so it is either one or the other.

I have two servers on the same domain, but one is set to not accept incoming mail. In the event of a disaster at our primary site, the back up server will then come into force.

I keep everything mirroed between the two using MS Interorganisation replication tool. This runs every night and replciates ALL mail and public folders over the VPN to the backup server.

mtmtechAuthor Commented:
Does this work if the domains are different?  For example, the current domain is and the new domain will be  So will the SMTP connector still forward mail to this other server if it's a totally different domain yet still on the same physical netowork and same subnet?
As long as the SMTP Connector is setup correctly the email will forward for a totally different domain.

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