We have a bit of a strange setup and I need some help/advice!
Our Exchange is part of SBS 2003. It's the only server for this company...
We're using the built-in POP Connector to pull down email from their host (mail.xyz.com) because we didn't want to purchase a bunch of spam protection and a backup mx subscription. Their mail host is providing email for free and do all the spam/virus scanning before it hits the server.
However, we can't use SMTP forwarding because our provider requires SMTP authentication.
So... I setup exch.xyz.com and pointed it to our static IP. The MX record points to mail.xyz.com.
Right now, I have the SMTP virtual server setup like this:
Masquerade domain: mail.xyz.com
Fully qualified domain name: exch.xyz.com
I have the external DNS addresses set to the ones our ISP provided.
At first we were getting kickbacks because I hadn't setup exch.xyz.com yet and was trying to totally masquerade as mail.xyz.com (including putting that into the FQDN field), but servers that did a reverse DNS lookup wasn't liking that the IP of the sender wasn't actually the IP address of mail.xyz.com. Lesson learned. That is when I added the exch.xyz.com and had the ISP make the lookup correct. I've verified that it works at www.DNSSTUFF.com
... a reverse lookup now gives our static IP.
We still seem to get kickbacks from a few certain domains. Is it bad to have a message coming from exch.xyz.com when the MX record points to mail.xyz.com? I didn't think it would matter, but I need the advice of an Expert.
If you need any other information, don't hesitate to ask... I will provide any details you may need!
Thank you very much in advance, Experts!