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RFC 3463 / ENHANCED MAIL STATUS

Use the registry and limit what a diagnostic reveals

05

Later documents add codes and registry rules. Consult the referenced definition rather than guessing from number shape, and remember that precise diagnostics can expose internal details.

DIAGRAMRead RFC section 5 ↗
RFC 3463 · § 5EXAMPLE
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Use the registry and limit what a diagnostic revealsThree registration and trust scenes. RFC3463 original standards-track-only text is updated by RFC5248Specification Required registry model. A definition collision is separated: older RFC4468X.7.8trust relationship required becomes X.7.14in RFC5248, while RFC4954uses5.7.8for invalid authentication credentials. Finally a plausible diagnostic is blocked from implying authenticated identity or authorized access; precise codes can disclose internal system details. No real credentials, reports or access decision are exercised.Check definitions; do not infer trustObserved delivery diagnosticinfer identity / grant accessMore detail can expose internal informationA status report is not authenticationConsult definitions and appropriate privacy controls
03
Stop an unwarranted trust inference.

A detailed status might expose mailbox or system information. Do not infer that the sender is genuine or access is authorized merely because a plausible status code is present.

Source for this drawing: RFC 3463 · Read RFC section 5 ↗

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Mail transport moves a message between servers. The message format describes its contents. Authentication adds checks; it does not make every message safe.

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Related RFCs and changes

“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.

What changed
RFC 3463 §2RFC 5248 §§2.1–2.3

The later update creates a registry and the Specification Required registration model; the original standards-track-only wording is not the whole current process.

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KEY POINT

A diagnostic is a report, not authentication or authorization.

  • RFC 5248 updates the original extension mechanism with an IANA registry using the Specification Required model. This replaces treating the original standards-track-only wording as the complete current registration process.
  • Definitions can be corrected to avoid collisions: RFC 5248 assigns Trust relationship required to X.7.14 in place of its prior X.7.8 use in RFC 4468. RFC 4954 uses 5.7.8 for invalid authentication credentials. Consult each code’s definition and applicable class.
  • RFC 3463 warns that more precise codes can disclose how internal mail systems are implemented. RFC 5248 also discusses security-response information leaks. The presence of a code does not authenticate the producer or authorize access.
DETAILS

The related-publication list is curated; official metadata separately records every formal update in the fetched snapshot. Later 3886/4468/4865/4954 extend tracking, submission/authentication or future-release behavior, not the basic dotted grammar. This guide is not a live registry mirror, a credential exchange or a privacy-control implementation.

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