Allow External Relay

Question

Hi, 
 I have 2 unrelated sites both running an Exchange behind 9.4 SMTP protection (not transparent) but I am having ISP issues at one site and would like to proxy in mail via the other. 
 So site1 gets dom1 mail and site2 gets dom2 mail, both with mx records in their respective external dns hosting. I would like to change the mx record for dom2 so it goes to site1, then want site1 to proxy this mail destined for dom2 to site2. Meanwhile site1 with still deal with dom1 mail as normal. 
 Can anyone give me pointers on how to go about this?

apijnappels · Accepted Answer

You'll need to work with SMTP Profiles on site 1. You can then configure two different profiles; 1 for dom1 and 1 for dom2 and have each profile deliver mails to the respective host.

BAlfson · Answer

Instead of changing the current MX-record for site 2, I would just add a lower-priority (higher number) MX-record that points at site 1. I have several clients set up so that their two different sites back each other up. You'd also need to make the corresponding changes to have site 2 backup site 1. 
 Cheers - Bob