I've set my reply-to email to coming into my Gmail account.
I'm assuming all the mail received will still go through Gmail server since I set that to be my reply-to address. Does that mean I'll see the reply in my email inbox, and CLOSEM is simply retrieving data or copied on the correspondence?
Yes, all the replies will go directly to your gmail account and appear in your inbox there. CLOSEM won't actually see that reply, at least not in this version. We are busy working on upgrades, which will have expanded capabilities, this included.