SMTP-CERT-MISMATCH
Mail server certificate does not match the MX hostname
What it means
Opportunistic TLS still works, but MTA-STS and DANE require a matching certificate, and some senders log or refuse mismatches.
How to fix it
- 1Issue a certificate that includes the MX hostname in its subject alternative names.
Re-check after the change
DNS changes can take up to the record's TTL to be seen; use Re-run on the result page to bypass our 10-minute cache.