X.7.22 · Security or policy
SMTP enhanced status code 5.7.22
No valid author-matched DKIM signature found
X.7.22 means no passing DKIM signature matched the domain in the From header, so author-domain checks failed.
| Registry code | X.7.22 |
|---|---|
| Forms in use | 5.7.22 |
| Registry name | No valid author-matched DKIM signature found |
| Subject | 7: Security or policy |
| Permanent or temporary | 5.x.x permanent failure: resending unchanged will not succeed |
| Associated basic codes | 550 |
| Defined in | [RFC 7372]; [RFC 6376] |
What the registry says
This status code is returned when a message contains one or more passing DKIM signatures, but none are acceptable because none have an identifier(s) that matches the author address(es) found in the From header field. This is a special case of X.7.21. (This violates the advice of [Section 6.1 of RFC 6376].)
IANA SMTP Enhanced Status Codes registry, X.7.22
The basic codes it travels with
- 550 Requested action not taken: mailbox unavailable (e.g., mailbox not found, no access, or command rejected for policy reasons)
In practice
X.7.22 is the alignment case: DKIM passed, but for a domain that does not match the From address. It is the DKIM half of DMARC alignment. Set up custom DKIM for the exact domain you send from. DMARC passes if either SPF or DKIM passes and aligns, but some receivers specifically want an author-matched DKIM signature, which survives forwarding better than SPF.
What the sender should do
Sign with a DKIM key on the same domain as the From address, so signature and author align.
Would verifying the list have prevented 5.7.22?
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 5.7.22 mean?
- X.7.22 means no passing DKIM signature matched the domain in the From header, so author-domain checks failed.
- What should I do about 5.7.22?
- Sign with a DKIM key on the same domain as the From address, so signature and author align.
- Would an email verifier have caught 5.7.22?
- 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
- IANA: SMTP Enhanced Status Codes registry (checked 2026-11-05)
- RFC 3463: Enhanced Mail System Status Codes (checked 2026-11-05)
- RFC 5321: Simple Mail Transfer Protocol, section 4.2.3 (reply codes) (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