Our organization runs Exchange 2007. We also have a Linux-based gateway that runs SendMail and Spam Assassin. We want to replace the Spam Assassin piece with either an appliance-based spam and virus scanning device, or move that function to the cloud using a service like Symantec’s Email Security.cloud.
Our accepted domain (which is also our authoritative domain) is mycompany.com. We have also a sub-domain called external.mycompany.com. We use this domain to allow a 3rd party mail service (i.e. Constant Contact) to send marketing email to our customers since we don’t want to allow CC to relay through our Exchange server. The 3rd party email service sends email with the return address of email@example.com. If any customer replies to firstname.lastname@example.org the incoming email is remapped in SendMail to email@example.com. In addition to moving away from Spam Assassin, we also want to discontinue this remapping function in SendMail (which was a band-aid fix to handle using this sub-domain).
The individual who originally setup Exchange did not configure the SMTP address space to accommodate sub-domains. And in their defense it wasn’t even a known need at the time.
As I understand it, if we were configuring Exchange for the first time we would have created an accepted domain with a wildcard character to tell Exchange that all sub-domains of the SMTP address space (mycompany.com) are to be accepted. Thusly we would have setup the SMTP address space as *.mycompany.com verses mycompany.com
Since I can’t edit my accepted domain, how do I now configure Exchange to accept email from this sub-domain (external.mycompany.com ) so it can be remapped (forwarded) to user accounts in my accepted domain (mycompany.com).
Thanks in advance.