550 5.7.1 – Unauthorised shipment
What does this error mean?
The SMTP server refuses the message for a reason of authorization, relay or policy.
Probable causes
- Unauthorised consignor
- Relay
- sender mismatch
- antispam or transport policy
Verification and resolution
- Read the full text after 550.57.1
- Compare the From address with the authenticated account
- Check the rights Send As or the relay rules
- Control SPF/DKIM only if message has already been accepted and rejected downstream
Precaution: Code 550 5.7.1 is generic: do not modify the DNS without reading the details of the rejection.