RFC 2821 · PROPOSED STANDARD · 2001
MON · 27 JUL 2026
Simple Mail Transfer Protocol
Overview
RFC 2821, “Simple Mail Transfer Protocol”, is a Proposed Standard document published in April 2001 by J. Klensin. It obsoletes RFC 821, RFC 974, RFC 1869. It has since been updated by RFC 5336. It has been obsoleted by RFC 5321 — refer to the newer document for the authoritative version. The canonical text is published by the RFC Editor.
Abstract
This document is a self-contained specification of the basic protocol for the Internet electronic mail transport. [STANDARDS-TRACK]
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
Read this RFC
The canonical text of RFC 2821 is hosted at rfc-editor.org. Available in TXT,HTML.
Relationships to other RFCs
Other RFCs from 2001
- RFC 2822 Internet Message Format
- RFC 2800 Internet Official Protocol Standards
- RFC 2899 Request for Comments Summary RFC Numbers 2800-2899
- RFC 2900 Internet Official Protocol Standards
- RFC 2919 List-Id: A Structured Field and Namespace for the Identification of Mailing Lists
- RFC 2961 RSVP Refresh Overhead Reduction Extensions
- RFC 2999 Request for Comments Summary RFC Numbers 2900-2999
- RFC 3000 Internet Official Protocol Standards