| starttls-not-supported |
This indicates that the recipient MX did not support STARTTLS. |
RFC 8460 |
| certificate-host-mismatch |
This indicates that the certificate presented did not adhere to the
constraints specified in the MTA-STS or DANE policy, e.g., if the MX hostname
does not match any identities listed in the subject alternative name (SAN)
RFC 5280. |
RFC 8460 |
| certificate-expired |
This indicates that the certificate has expired. |
RFC 8460 |
| tlsa-invalid |
This indicates a validation error in the TLSA record associated
with a DANE policy. None of the records in the RRset were found to be valid. |
RFC 8460 |
| dnssec-invalid |
This indicates that no valid records were returned from the recursive
resolver. |
RFC 8460 |
| dane-required |
This indicates that the sending system is
configured to require DANE TLSA records for all the MX hosts of
the destination domain, but no DNSSEC-validated TLSA records were
present for the MX host that is the subject of the report. Mandatory DANE for SMTP is
described in Section 6 of RFC 7672.
Such policies may be created by mutual agreement between two
organizations that frequently exchange sensitive content via email. |
RFC 8460 |
| certificate-not-trusted |
This is a label that covers multiple
certificate-related failures that include, but are not limited to,
errors such as untrusted/unknown certification authorities (CAs),
certificate name constraints, certificate chain errors, etc. When
using this declaration, the reporting MTA SHOULD utilize the
"failure-reason-code" to provide more information to the receiving entity. |
RFC 8460 |
| sts-policy-invalid |
This indicates a validation error for the overall MTA-STS Policy. |
RFC 8460 |
| sts-webpki-invalid |
This indicates that the MTA-STS Policy could
not be authenticated using PKIX validation. |
RFC 8460 |
| validation-failure |
This indicates a general failure for a
reason not matching a category above. When using this
declaration, the reporting MTA SHOULD utilize the "failure-reason-code"
to provide more information to the receiving entity. |
RFC 8460 |
| sts-policy-fetch-error |
This indicates a failure to retrieve an
MTA-STS policy, for example, because the policy host is unreachable. |
RFC 8460 |
