Enforce tag-only mode at the outbound transport boundary

When an inbox must keep classification while suppressing automated replies, retain ingestion and category updates but enforce an explicit reply policy at every outbound transport boundary. Recipient-suffix exceptions can defeat a nominal no-reply mode, particularly when a message contains several recipients. A dedicated classification-only path should stop before owner-dependent negotiation and generation, while the transport guard protects helper paths, retries, and future callers. Verify category writes alongside zero outbound reply, forward, and send operations. This establishes code behavior; deployment provenance and mailbox routing still need separate verification.

Applies when: A monitored inbox needs automated classification without outgoing messages. Keywords: inbox tagging replies suppression transport mixed recipients retries classification