5.7.512 Microsoft bounce: from address missing
What 5.7.512 means
The message was sent without a valid From email address, which Microsoft 365 requires.
Message text
Access denied, message must be RFC 5322 section 3.6.2 compliant
Common causes of 5.7.512
- Message has no valid email address in the From header
How to fix 5.7.512
- Put a valid address in the From header, in angle brackets, for example <[email protected]>.
- Check the From domain with DMARC checker so that it matches the domain you authenticate.
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How to read 5.7.512
The second part, 5.7.512, 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 5.7.512 mean?
The message was sent without a valid From email address, which Microsoft 365 requires. This is a permanent failure.
How do I fix 5.7.512?
Put a valid address in the From header, in angle brackets, for example <[email protected]>. Check the From domain with DMARC checker so that it matches the domain you authenticate.
Is 5.7.512 permanent, and should I retry?
5.7.512 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.