Electronic Mail InfoUnlike most Internet transport protocols, EMail does not have a single specification for getting and sending messages, but two: Simple Mail Transfer Protocol (SMTP) and Post Office Protocol (POP).
Other protocols are defined for managing electronic mailboxes: Internet Mail Access Protocol (IMAP), and still others for resolving mail addresses: Domain Name Service (DNS).
This page provides links to the various EMail-related RFCs.
Sending MailSimple Mail Transfer Protocol (SMTP) - RFC0821
SMTP Message Size Extension - RFC1870
EMail Content Types - RFC1049
Multipurpose Internet Mail Extentions (MIME)
Message PackagingMulti-Part MIME - RFC2045
Getting MailPost Office Protocol - Version 3 (POP3) - RFC1939
Post Office Protocol - Version 2 (POP2) - RFC0937
Mail Address ResolutionDomain Name Server - MX (DNS-MX) - RFC0974
Mailbox AdministrationInternet Message Access Protocol - Version 4 (IMAP4) - RFC1730
Internet Mail Access Protocol - Version 3 (IMAP3) - RFC1203
IMAP4 Authentication - RFC1731
EMail PrivacyPrivacy Enhancement for Internet MAIL (PEM) - RFC1421
PEM Certificate-based Key Management - RFC1422
PEM Algorithms, Modes and Identifiers - RFC1423
PEM Key Certification - RFC1424
For comments/correction/additions regarding this reference, email email@example.com.