Envelope vs message
01SMTP transports an envelope and message content. Visible To and From headers do not define the transport envelope.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 2.3.1 ↗
RFC 5321 · § 2.3.1EXAMPLE
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04
Keep blind recipients private.
Delivery does not require copying every envelope recipient into the message headers.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Read the updated RFC section ↗
Route with the envelope; display the message.
- MAIL FROM sets the reverse-path; RCPT TO supplies each forward-path.
- Message headers and body follow message-format rules such as RFC 5322.
- Blind-copy recipients can appear in the envelope without appearing in the visible headers.
Do not infer a required one-to-one relationship between envelope addresses and header addresses, or expose all RCPT recipients in a trace field.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
Privacy