Dedicated sendmail email delivery server
Scenario: I have a client that has migrated their email to Google Apps and now is using Googles MX servers for incoming email to their domain. Part of their application sends out emails daily (about 27,000 of them) and, unfortunately, Google doesnt allow that many to be sent out from its servers. This becomes an issue because some spam filters apparently check MX records for the senders domain to make sure the email isnt spoofed, so we cant send the emails directly from their application without relaying it through a "legit" email server.
Possible solution: Can i configure an inhouse linux server using sendmail as a delivery agent, allow relaying from the application server, add an MX record pointing to it, and have it only accept incoming emails for my clients domains but relay them to Google. Ill add the MX record with low priority to minimize the chance of it receiving any incoming, but it could still happen.
Is my solution feasible? Or would another approach work better? Any suggestions or advise is welcome.
BTW: although im very familiar with Linux, sendmail is still a blind-spot for me. I have very little working knowledge of it.