Simple Mail Transfer Protocol
RFC 821, “Simple Mail Transfer Protocol”, is an Internet Standard document published in August 1982 by J. Postel. It obsoletes RFC 788. It has been obsoleted by RFC 2821 — refer to the newer document for the authoritative version. The canonical text is published by the RFC Editor.
Abstract
The objective of Simple Mail Transfer Protocol (SMTP) is to transfer mail reliably and efficiently. SMTP is independent of the particular transmission subsystem and requires only a reliable ordered data stream channel. Obsoletes RFC 788, 780, and 772.
What “Internet Standard” means
A mature, widely-implemented specification that has completed the full IETF standards process — the highest maturity level on the standards track.
The canonical text of RFC 821 is hosted at rfc-editor.org. Available in TXT,HTML.
- RFC 820 Assigned numbers
- RFC 822 STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES
- RFC 819 The Domain Naming Convention for Internet User Applications
- RFC 823 DARPA Internet gateway
- RFC 818 Remote User Telnet service
- RFC 824 CRONUS Virtual Local Network
- RFC 817 Modularity and efficiency in protocol implementation
- RFC 825 Request for comments on Requests For Comments