5.7.1 SMTP bounce: delivery not authorized
What 5.7.1 means
The receiver refuses delivery because the sender is not allowed to send to this destination, for example through per-host or per-recipient filtering.
Message text
Delivery not authorized, message refused
Common causes of 5.7.1
- Receiver's policy refuses mail from your sending IP or domain
- Sender is not on the recipient's allowed-senders list
How to fix 5.7.1
- Check authentication with SPF checker, DKIM checker and DMARC checker.
- Check your sending IP with blocklist check.
- If you should be allowed, ask the recipient's administrator to allow your sender.
Check your domain
Check the SPF record of your sending domainRuns in your browser; nothing is uploaded.
Have the full bounce message? Paste it into the bounce code lookup and it will match the code and the provider for you. Open the bounce code lookup.
How to read 5.7.1
The second part, 5.7.1, is an enhanced status code (RFC 3463 §2) written class.subject.detail. Class 5 is a Permanent failure (5xx): the command was rejected and the sender should not repeat it unchanged (RFC 5321 §4.2.1; RFC 3463 §2).. Subject 7 is security or policy: authentication, authorization or policy refused the message. The detail number refines the subject, and providers may define details of their own, which is why one code can read differently at Gmail, Microsoft and Yahoo.
Do not keep resending the same message: a permanent failure repeats until the cause is fixed. Correct the cause, then send a new message.
Official source: www.rfc-editor.org. Last verified 2026-10-20.
Related guides
- How to create an SPF record (syntax and examples)
- How DKIM works and how to publish a DKIM record
- How to set up a DMARC record, from p=none to p=reject
Related codes
- 550 5.7.1 Gmail: likely unsolicited
- 550 5.7.1 Microsoft: delivery not authorized
- 550 5.7.1 Microsoft: unable to relay
- 530 5.7.1 Microsoft: not authenticated
- 5.7.0 SMTP: security status
- 5.7.23 SMTP: SPF validation failed
FAQ
What does 5.7.1 mean?
The receiver refuses delivery because the sender is not allowed to send to this destination, for example through per-host or per-recipient filtering. This is a permanent failure.
How do I fix 5.7.1?
Check authentication with SPF checker, DKIM checker and DMARC checker. Check your sending IP with blocklist check. If you should be allowed, ask the recipient's administrator to allow your sender.
Is 5.7.1 permanent, and should I retry?
5.7.1 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.