Which identity SPF checks
01SPF evaluates the connecting IP against an SMTP identity’s domain.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 2.4 ↗
RFC 7208 · § 2.4EXAMPLE
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03
Evaluate authorization
Check whether that IP is authorized by that domain’s SPF policy.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
RFC 4408 experimental SPFRFC 7208 §3.1
SPF policies now use DNS TXT only; use of the dedicated SPF RR type 99 is removed.
Read the updated RFC section ↗MAIL FROM is an envelope identity, not necessarily the visible From header.
- MAIL FROM is an envelope identity, not necessarily the visible From header.
- HELO checking has its own defined role, including null reverse-path handling.
- SPF does not authenticate arbitrary message content.
Examples are illustrative. Consult the linked RFC and its errata for implementation details.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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