How does Reply Mail Management (RMM) work, and what are the reply address type options?

RMM (Reply Mail Management) is the SAP component that manages inbound replies to marketing emails. When a subscriber hits "Reply" on an email, instead of going directly to an inbox, the reply is processed by Marketing Cloud's RMM system first.
Reply-to address types:
— No-Reply address: Replies are processed by RMM; out-of-office and auto-replies are discarded. Human replies can be forwarded to a specified mailbox.
— Profile reply-to: The reply goes to the email address defined in the Sender Profile.
— Custom reply-to address: A specific email address defined per email or send classification.
Automatic unsubscribe actions: RMM can scan reply email subjects/bodies for unsubscribe keywords (e.g., "unsubscribe", "remove me") and automatically unsubscribe the replying contact, ensuring compliance even for subscribers who reply instead of clicking the unsubscribe link.
Out-of-office filtering: Auto-reply messages (vacation responders) are identified and discarded to avoid cluttering the forwarding mailbox.