- Shipped
- September 12, 2026 at 1:33 AM UTC
- Author
- Kamo
- Commit
- d397338
The relay sends only as its own domain and answers anything else with a 451, so a campaign whose From is on another domain used to retry every recipient three times, each retry a warm-up attempt, before anyone learned the From was wrong. When the org's provider is the relay's host and port and the From's domain is not the relay's sending domain, the recipient is now marked FAILED with the fix in its error: no SMTP, no retry, no suppression, and nothing counted against the warm-up or its slot.