SMTP Resources

SMTP - A Tutorial

SMTP tutorial covering the Simple Mail Transfer Protocol and including sending a message; SMTP commands; a breakdown of envelope, header and body; and relay agents. Includes some diagrams.

SMTP: Simple Mail Transfer Protocol

"These pages are designed as a reference for the Simple Mail Transfer Protocol (SMTP). They cover today's SMTP implementations and the IETF SMTP specifications, including some SMTP extensions."

All About Email Headers

This is a page at stopspam.org that has a lot of useful information about email headers and some stuff about smtp commands.

Email Protocols : SMTP, MIME, POP and IMAP

These are presentation slides including information about smtp, and the other email protocols.

SMTP RFC

Yahoo listing of RFCs for SMTP.