Locking down port 25 for just some domains?

[Toad21]

Hello,

OK here is the scenerio. I need to lock down port 25 (smtp) for just a few email domains on an exchange 2003 box. Right now, we host 57 email domains, and 9 of them need to only have mail come in from MXLogic. MXLogic wants me to lock it down at the firewall level and or the exchange level, but that would lock it down for all of our clients, and I need to only lock it down for those 9. Is there anyway to lock down port 25 on just the a few clients on exchange server? I know most people don't have multiple domains on 1 exchange, but we do. Maybe on the DNS server there is a forward lookup rule I can create? Any help appreciated.

Thank you for your time,

-Todd Thomas
Network Engineer
MCS Office Technologies
tthomas@mcsot.com

 

[ShackDaddy]

Do you have an extra IP address to work with? If you changed the MX for those 9 domains to point at that IP, you could then (depending on what you are running for a firewall) block inbound port 25 traffic from any source except for the subnets you are expecting MX-logic traffic from. This is probably the easiest way.

Or maybe you could create another virtual SMTP server on your Exchange install that listens on an alternate port and have MXLogic use that alternate port when sending mail to your domains. You'd have to set an alternate FQDN for that virtual server, and create an address for that server in your internal DNS. This is complicated, and there are more configurations than I've mentioned involved, so ask back here if you are actually interested in going this route.

ShackDaddy