I basically want to have two separate email servers. The first one is the GoogleApps GMail service, which is for humans to use. The second server would be for sending messages from my application (so, send them programatically).
Do I even need to reference second mail server (on the same IP as my application) in MX-records (or wherever this would have to be referenced)? I wouldn't like the emails to get flagged spam or as "suspicious."
On a side note, I might use this mail server to process some "special" types of messages (like all messages sent to firstname.lastname@example.org). I found a related question for this, but I am not sure it is what I am looking for.