Resend Webhook

Delivery events from Resend — the half of sending Admiral was deaf to.

Resend returns 200 the moment it ACCEPTS a message. The bounce or the spam complaint arrives here, minutes later, and until this endpoint existed nothing in the product ever learned that a send had failed at the far end. A dead owner address kept getting the daily low-balance mail indefinitely, which is exactly the pattern mailbox providers read as an unmaintained list — and Resend's acceptable-use policy attaches account closure to the resulting numbers.

Answers 200 to anything it understands OR safely ignores, so Resend stops retrying; only a bad signature is refused.