Enhanced SMTP status code · RFC 3463 · IANA
5.7.322 certificate-expired: Destination mail server's certificate is expired
The recipient's domain uses DANE, and its server's certificate has expired.
- Class: Permanent failure
Class 5: a permanent failure. Resending the same message will not help: something about the message, the sender or the destination must change (RFC 3463 §3.1).
Also seen as:
4.7.322 - Subject: X.7 · Security and policy
Policies (per-host or per-recipient filters) and cryptographic operations; up to the sender, the recipient or both.
How 5.7.322 appears at providers
The exact text from the provider's documentation, as you see it in the bounce, and what it means.
Microsoft 365 / Exchange Online
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5.7.322
certificate-expired: Destination mail server's certificate is expired.
The recipient's domain uses DANE, and its server's certificate has expired. Check with SMTP server check.
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4.7.322
certificate-expired: Destination mail server's certificate is expired.
The recipient's domain uses DANE, and its server's certificate has expired. Check with SMTP server check.
What you can check here
Have the whole error message?
Sources: RFC 5321 · RFC 3463 · RFC 3464 · IANA · Gmail · Microsoft 365 · read on 26 September 2026