Date Host Info
2026-10-28 19:12:34 Hard Bounce mail.stalw.art [135.181.195.209] 550 5.1.1 Mailbox does not exist.
2026-10-28 19:12:25 Processed mail.domain.tld [IPv4] Received by mail.smtp2go.com ([email protected] -> [email protected])
Please let me know if more detailed logs are needed, I can directly send them.
I have reviewed the documentation and FAQ and confirm that my issue is NOT addressed there.
on
I have searched this support forum (open and closed topics) and confirm this is not a duplicate.
on
I understand that topics in this category are triaged by a bot first but a human reply will follow up. If I’d prefer a human-only reply, I’ll add the no-ai tag to my topic.
This looks like a problem on the stalwart.email side, not in your own setup. Your DMARC report was delivered to mail.stalw.art, the MX for stalwart.email, and that server answered 550 5.1.1 Mailbox does not exist for [email protected]. In other words, nobody has created a postmaster account or alias for that domain on the receiving server. Your sending side did its job. SMTP2GO processed the message and handed it off correctly.
I didn’t search the docs or source for this reply, so I can’t point to any Stalwart setting that explains the rejection. The reply doesn’t depend on your version. You’re running v0.16.x, and the answer for v1.0 may differ. If you do upgrade, the guide is here: Overview | Stalwart
This isn’t covered in the current docs. A community member or staff member will follow up.
This is an automated reply from the Stalwart Help Bot. Other community members may follow up if this answer is incomplete or wrong.
The rua address in the stalwart.email DMARC record didn’t point at a mailbox that existed on our server, so every aggregate report bounced. That’s fixed now, and reports to [email protected] should be accepted from here on. If your next one still bounces, post the new bounce line here and I’ll take another look.