POP3
- RFC 1939 - Post Office Protocol (version 3)
- RFC 2449 - POP3 Extension Mechanism
- RFC 1734 - POP3 AUTHentication command
POP3 and IMAP Specifications
- RFC 2195 - IMAP/POP AUTHorize Extension for Simple Challenge/Response
- RFC 2595 - Using TLS with IMAP, POP3 and ACAP
SMTP specifications
- RFC 2821 - Simple Mail Transfer Protocol
- RFC 821 - Simple Mail Transfer Protocol (obsolete)
- RFC 822 - Format of ARPA Internet text messages
- RFC 974 - Mail routing and the domain system
- RFC 3501 - Internet message access protocol (version 4rev1)
- RFC 3848 - ESMTP and LMTP Transmission Types Registration
SMTP service extensions
- RFC 2821 - Simple Mail Transfer Protocol
- RFC 1869 - SMTP Service Extensions
- RFC 2554 - SMTP Service Extension for Authentication
- RFC 1830 - SMTP Service Extensions for Transmission of Large and Binary MIME Messages
- RFC 2920 - SMTP Service Extension for Command Pipelining
- RFC 1652 - SMTP Service Extension for 8bit-MIME transport
- RFC 1870 - SMTP Service Extension for Message Size Declaration
IMAP specifications
- RFC 3501 - INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1
- RFC 2342 - IMAP4 Namespace
- RFC 2180 - IMAP4 Multi-Accessed Mailbox Practice
- RFC 2683 - IMAP4 Implementation Recommendations
- RFC 2087 - IMAP4 QUOTA extension
- RFC 2359 - IMAP4 UIDPLUS extension
- RFC 2088 - IMAP4 non-synchronizing literals
- RFC 2177 - IMAP4 IDLE command
- RFC 3502 - Internet Message Access Protocol (IMAP) - MULTIAPPEND Extension
- RFC 3348 - The Internet Message Action Protocol (IMAP4) Child Mailbox Extension
- RFC 4314 - IMAP4 Access Control List (ACL) Extension
- RFC 6154 - IMAP LIST Extension for Special-Use Mailboxes (partial support)
HTTP specifications
- RFC 2616 - Hypertext Transfer Protocol -- HTTP/1.1
- RFC 2965 - HTTP State Management Mechanism
- RFC 2396 - Uniform Resource Identifiers (URI): Generic Syntax
DNS specifications
- RFC 1034 - Domain names, Concepts and Facilities
- RFC 1035 - Domain names, Implementation and Specification
SIEVE extensions implemented in Axigen
- RFC 3028 - SIEVE: A Mail Filtering Language (Extensions defined in the base RFC: fileinto, reject, envelope)
- RFC 3894 - SIEVE Extension: Copying without Side Effects
- RFC 3431 - SIEVE Extension: Relational Tests; Comparator extension: i;numeric-comparator
- RFC 3598 - SIEVE Email Filtering -- Subaddress Extension
Generic RFCs
- RFC 2822 - Internet message format
- RFC 2045 - MIME Part One: Format of Internet Message Bodies
- RFC 2046 - MIME Part Two: Media Types
- RFC 2047 - MIME Part Three: Message Header Extensions for Non-ASCII Text
Mailing Lists
- RFC 2919 - List-Id: A Structured Field and Namespace for the Identification of Mailing Lists
- RFC 2369 - The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header * Fields
FTP
- RFC 959 - FILE TRANSFER PROTOCOL (FTP)
Groupware
- RFC 2445 - Internet Calendaring and Scheduling Core Object Specification (iCalendar)
- RFC 2446 - iCalendar Transport-Independent Interoperability Protocol (iTIP) Scheduling Events, BusyTime, To-dos and Journal Entries
- RFC 2447 - iCalendar Message-Based Interoperability Protocol (iMIP)
- RFC 3283 - Guide to Internet Calendaring
- RFC 2426 - vCard MIME Directory Profile
SNMP
- RFC 1157 - A Simple Network Management Protocol (SNMP)
- RFC 3416 - Version 2 of the Protocol Operations for the Simple Network Management Protocol (SNMP)
- RFC 1213 - Management Information Base for Network Management of TCP/IP-based internets: MIB-II
- RFC 3418 - Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)