Reference
Smarter bounce handling
Emailit matches bounce messages to the original email, treats common mailbox-full replies as permanent, and backs off from servers that throttle or block.
Updated Dec 13, 2025
ImprovedDeliverability
- Bounce messages that arrive after delivery are matched to the original email, which is then marked
bounced. - Over-quota, unknown-user and disabled-mailbox replies sent with temporary
4xxcodes are treated as hard bounces instead of being retried. - After a
451reply, Emailit pauses delivery from that IP to that recipient domain for 5 minutes, and for 1 hour after a550 5.7.1block.
See Bounce categories.