Microsoft 365 5.7.23
The message was rejected because of Sender Policy Framework violation
Microsoft 365 5.7.23 means: the message was rejected because of Sender Policy Framework violation. It is a permanent failure, so do not retry it unchanged. The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
Microsoft 365’s exact wording
Quoted from Microsoft Learn: Email non-delivery reports and SMTP errors in Exchange Online, checked 2026-11-05. Placeholders are Microsoft 365’s own.
Provider's description
The message was rejected because of Sender Policy Framework violation
Possible cause
The destination email system uses SPF to validate inbound mail, and an issue affects your SPF configuration.
| Who sends it | Microsoft 365, Exchange Online and Outlook.com |
|---|---|
| Basic code | Microsoft 365 lists the enhanced code only |
| Enhanced code | 5.7.23: SPF validation failed |
| Permanent or temporary | Permanent (5xx) |
| Verifying the list prevents it | No |
In practice
550 5.7.23 means the destination checked SPF and your configuration failed. Exchange Online customers see it when sending to domains that enforce SPF, and also when a third-party service sends as their domain without being in the SPF record. Add every legitimate sending service and keep the record within 10 lookups. Microsoft's text says the destination uses SPF to validate inbound mail. Test your record with an SPF checker. Remember that forwarding can break SPF, so a message forwarded through another server may fail even when your own record is correct.
What the sender should do
The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
Would verifying the list have prevented Microsoft 365 5.7.23?
No
This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Common questions
- What does Microsoft 365 5.7.23 mean?
- Microsoft 365 5.7.23 means: the message was rejected because of Sender Policy Framework violation. It is a permanent failure, so do not retry it unchanged. The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
- Should I retry after Microsoft 365 5.7.23?
- No. It is a permanent (5xx) failure, so the same message to the same address will fail again. Fix the cause first. The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
- Would verifying my list have prevented Microsoft 365 5.7.23?
- No. This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Sources
- Microsoft Learn: Email non-delivery reports and SMTP errors in Exchange Online (checked 2026-11-05)
- IANA: SMTP Enhanced Status Codes registry (checked 2026-11-05)
Registry and provider wording is quoted exactly; guidance is written by the SimpleVerifier Team.
SimpleVerifier Team · Last checked against the sources 2026-11-05