Reply Mail Management ' s auto-reply functionality is configured to respond back to the original sender using the same From Address that the original marketing send used — in this case, marketing@email.nto.com — because from the customer ' s perspective, their reply was addressed to that sending domain, and the automatic acknowledgment they receive should logically and consistently come from that same recognizable address rather than an internal, customer-facing forwarding destination. This maintains a coherent sender identity for the customer even though, behind the scenes, RMM is simultaneously forwarding the actual reply content to the internal Customer Service team ' s inbox (customerservice@nto.com) for follow-up. Option D, customerservice@nto.com, is the internal destination the reply content gets forwarded to for the Customer Success team ' s visibility — it is not the address the customer ' s automatic acknowledgment appears to come from. Option A, customer@example.com, is the customer ' s own address and the recipient of the auto-reply, not its sender. Option B, a generic ' reply@marketingcloud.com, ' is not a real, functional Marketing Cloud sending address and does not correspond to how RMM auto-reply From Address configuration actually works. Reference: Reply Mail Management, Auto-Reply Configuration.