Does “delivered” mean “inboxed”?

Myth: Delivered means the message reached the inbox.

Reality: Delivered only means the receiving server accepted the message. It tells you nothing about where it landed.

A message can be delivered and:

Land in the primary inbox. Land in spam folder. Go to Promotions or other tabs. End up in corporate quarantine. Be silently discarded by post-acceptance filtering.

Delivery rate is necessary but not sufficient. Inbox placement requires separate measurement.

Delivered means the harbor accepted your ship. It does not tell you which dock you were assigned.