5.7.800 Microsoft bounce: sender domain banned
What 5.7.800 means
The sending domain in the message was banned by Exchange Online because of detected spam activity.
Message text
Access denied, banned sender
Common causes of 5.7.800
- EHLO, P1 or P2 sender domain was banned after spam was detected from it
How to fix 5.7.800
- Check that the domain is not compromised and that its mail is authenticated with SPF checker and DKIM checker.
- Contact Microsoft support to restore the domain's ability to send.
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How to read 5.7.800
The second part, 5.7.800, 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: learn.microsoft.com. 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
- 5.7.0 SMTP: security status
- 5.7.1 SMTP: delivery not authorized
- 5.7.23 SMTP: SPF validation failed
- 5.7.25 SMTP: reverse DNS failed
- 5.7.26 SMTP: authentication failed
- 5.7.27 SMTP: sender has null MX
FAQ
What does 5.7.800 mean?
The sending domain in the message was banned by Exchange Online because of detected spam activity. This is a permanent failure.
How do I fix 5.7.800?
Check that the domain is not compromised and that its mail is authenticated with SPF checker and DKIM checker. Contact Microsoft support to restore the domain's ability to send.
Is 5.7.800 permanent, and should I retry?
5.7.800 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.