5.7.1 error: Delivery not authorised - message refused
The most common policy rejection. 5.7.1 says only that the receiver refused the message for a policy reason - reputation, blocklist, authentication or content. The text after the code tells you which.
How to fix 5.7.1
- Read the full line after 5.7.1: look for a blocklist name, 'SPF', 'DMARC', 'IP reputation' or a URL.
- Check the sending IP and domain on blacklists and test authentication.
- If the text is only 'refused', run the email through the Spam Test.
Why this happens
The receiving server refused the message under a policy rule and the code alone doesn't say which one. The explanatory text after the code is where the actual reason - a blocklist, authentication, content or reputation - is named.
How to keep it from coming back
Keep authentication correct, stay off blocklists, send to engaged recipients and test messages before sending. Always keep the full bounce text, because it is what identifies the rule that fired.
Should I retry a 5.7.1 error?
Not as it stands. A permanent error means the same message will be refused again until the cause is fixed on your side. Fix the cause first, then send a fresh message; if it keeps failing after that, check the full text of the bounce for the exact reason.
Got the full bounce message?
The text after the code names the exact reason, and the same code can mean different things at different receivers. Paste the whole message into the decoder - it runs in your browser and nothing is sent.
Open the bounce decoderRelated error codes
Seeing this again and again? That's usually a reputation or authentication problem we can trace and fix at the source.
How we help: Consulting · Private infrastructure · Managed mailboxes · Monthly support