1) Email Bible: Internet Email Protocols: A Developer's Guide [Paperback] by Kevin Jhonson
2) Top-Down Overview: Wood, D (1999). Programming Internet Mail. O'Reilly
3) Uses VB Source: Rhoton, J (1999). Programmer's Guide to Internet Mail: SMTP, POP, IMAP, and LDAP
4) Totally NT Oriented: Hughes, L (1998). Internet e-mail Protocols, Standards and Implementation. Artech House Publishers
Post Office Protocol - Wikipedia, the free encyclopedia
RFC 1081 - Post Office Protocol Version 3
RFC 2449 - POP3 Extension Mechanism
RFC 2595 - Using TLS with IMAP, POP3 and ACAP
RFC 2616 - Hypertext Transfer Protocol -- HTTP-1.1
RFC 2822 - Internet Message Format
RFC 3164 - The BSD Syslog Protocol
RFC 3207 - SMTP Service Extension for Secure SMTP over Transport Layer Security
RFC 3507 - Internet Content Adaptation Protocol (ICAP)
RFC 5034 - The Post Office Protocol (POP3) Simple Authentication and Security Layer (SASL) Authentication Mechanism
RFC 5321 - Simple Mail Transfer Protocol
