RFCs

Specifications

The following IETF specifications define the IMAP, POP3 and SMTP protocols:

• 821: SIMPLE MAIL TRANSFER PROTOCOL
• 822: STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES
• 974: MAIL ROUTING AND THE DOMAIN SYSTEM
• 1081: Post Office Protocol - Version 3
• 1123: Requirements for Internet Hosts -- Application and Support
• 1225: Post Office Protocol - Version 3 (Obsoletes rfc1081)
• 1425: SMTP Service Extensions
• 1426: SMTP Service Extension for 8bit-MIME transport
• 1460: Post Office Protocol - Version 3 (Obsoletes rfc1225)
• 1651: SMTP Service Extensions (Obsoletes rfc1425)
• 1652: SMTP Service Extension for 8bit-MIME transport (Obsoletes rfc1426)
• 1653: SMTP Service Extension for Message Size Declaration
• 1725: Post Office Protocol - Version 3 (Obsoletes rfc1460)
• 1730: INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4
• 1731: IMAP4 Authentication Mechanisms
• 1734: POP3 AUTHentication command
• 1830: SMTP Service Extensions for Transmission of Large and Binary MIME Messages
• 1854: SMTP Service Extension for Command Pipelining
• 1870: SMTP Service Extension for Message Size Declaration (Obsoletes rfc1653)
• 1869: SMTP Service Extensions
• 1891: SMTP Service Extension for Delivery Status Notifications
• 1928: SOCKS Protocol Version 5
• 1929: Username/Password Authentication for SOCKS V5
• 1939: Post Office Protocol - Version 3 (Obsoletes rfc1725)
• 1961: GSS-API Authentication Method for SOCKS Version 5
• 2034: SMTP Service Extension for Returning Enhanced Error Codes
• 2060: INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1 (Obsoletes rfc1730)
• 2086: IMAP4 ACL extension
• 2087: IMAP4 QUOTA extension
• 2088: IMAP4 non-synchronizing literals
• 2095: IMAP/POP AUTHorize Extension for Simple Challenge/Response
• 2177: IMAP4 IDLE command
• 2193: IMAP4 Mailbox Referrals
• 2195: IMAP/POP AUTHorize Extension for Simple Challenge/Response (Obsoletes rfc2095)
• 2197: SMTP Service Extension for Command Pipelining (Obsoletes rfc1854)
• 2221: IMAP4 Login Referrals
• 2222: Simple Authentication and Security Layer (SASL)
• 2245: Anonymous SASL Mechanism
• 2342: IMAP4 Namespace
• 2359: IMAP4 UIDPLUS extension
• 2449: POP3 Extension Mechanism (Updates rfc1939)
• 2487: SMTP Service Extension for Secure SMTP over TLS
• 2554: SMTP Service Extension for Authentication
• 2595: Using TLS with IMAP, POP3 and ACAP
• 2683: IMAP4 Implementation Recommendations
• 2821: Simple Mail Transfer Protocol (Obsoletes rfc0821, rfc0974, rfc1869) (Updates rfc1123)
• 2822: Internet Message Format (Obsoletes rfc0822)
• 2831: Using Digest Authentication as a SASL Mechanism
• 2920: SMTP Service Extension for Command Pipelining (Obsoletes rfc2197)
• 2971: IMAP4 ID extension
• 3030: SMTP Service Extensions for Transmission of Large and Binary MIME Messages (Obsoletes rfc1830)
• 3207: SMTP Service Extension for Secure SMTP over Transport Layer Security (Obsoletes rfc2487)
• 3348: The Internet Message Action Protocol (IMAP4) Child Mailbox Extension
• 3461: Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) (Obsoletes rfc1891)
• 3501: INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1 (Obsoletes rfc2060)
• 3502: Internet Message Access Protocol (IMAP) - MULTIAPPEND Extension
• 3516: IMAP4 Binary Content Extension
• 3691: Handle System Namespace and Service Definition
• 4013: SASLprep: Stringprep Profile for User Names and Passwords
• 4314: IMAP4 Access Control List (ACL) Extension (Obsoletes rfc2086)
• 4315: Internet Message Access Protocol (IMAP) - UIDPLUS extension (Obsoletes rfc2359)
• 4466: Collected Extensions to IMAP4 ABNF (Updates rfc2088, rfc2342, rfc3501, rfc3502, rfc3516)
• 4469: Internet Message Access Protocol (IMAP) CATENATE Extension (Updates rfc3501, rfc3502)
• 4505: Anonymous Simple Authentication and Security Layer (SASL) Mechanism (Obsoletes rfc2245)
• 4551: IMAP Extension for Conditional STORE Operation or Quick Flag Changes Resynchronization (Updates rfc3501)
• 4616: The PLAIN Simple Authentication and Security Layer (SASL) Mechanism (Updates rfc2595)
• 4731: IMAP4 Extension to SEARCH Command for Controlling What Kind of Information Is Returned
• 4952: Overview and Framework for Internationalized Email
• 4959: IMAP Extension for Simple Authentication and Security Layer (SASL) Initial Client Response
• 4978: The IMAP COMPRESS Extension
• 5032: WITHIN Search Extension to the IMAP Protocol (Updates rfc3501)
• 5161: The IMAP ENABLE Extension
• 5162: IMAP4 Extensions for Quick Mailbox Resynchronization
• 5182: IMAP Extension for Referencing the Last SEARCH Result (Updates rfc3501)
• 5255: Internet Message Access Protocol Internationalization
• 5256: Internet Message Access Protocol - SORT and THREAD Extensions
• 5257: Internet Message Access Protocol - ANNOTATE Extension
• 5258: Internet Message Access Protocol version 4 - LIST Command Extensions (Obsoletes rfc3348) (Updates rfc2193)
• 5259: Internet Message Access Protocol - CONVERT Extension
• 5267: Contexts for IMAP4
• 5321: Simple Mail Transfer Protocol (Obsoletes rfc2821) (Updates rfc1123)
• 5336: SMTP Extension for Internationalized Email Addresses (Updates rfc2821, rfc2822, rfc4952)
• 5464: The IMAP METADATA Extension
• 5465: The IMAP NOTIFY Extension (Updates rfc5267)
• 5466: IMAP4 Extension for Named Searches (Filters)
• 5530: IMAP Response Codes
• 5721: POP3 Support for UTF-8
• 5738: IMAP Support for UTF-8 (Updates rfc3501)
• 5788: IMAP4 Keyword Registry
• 5801: Using Generic Security Service Application Program Interface (GSS-API) Mechanisms in Simple Authentication and Security Layer (SASL): The GS2 Mechanism Family
• 5802: Salted Challenge Response Authentication Mechanism (SCRAM) SASL and GSS-API Mechanisms
• 5819: IMAP4 Extension for Returning STATUS Information in Extended LIST
• 5957: Display-Based Address Sorting for the IMAP4 SORT Extension (Updates rfc5256)
• 6154: IMAP LIST Extension for Special-Use Mailboxes
• 6203: IMAP4 Extension for Fuzzy Search
• 6237: IMAP4 Multimailbox SEARCH Extension (Obsoletes rfc4466)
• 6531: SMTP Extension for Internationalized Email (Obsoletes rfc5336)
• 6851: Internet Message Access Protocol (IMAP) - MOVE Extension
• 6855: IMAP Support for UTF-8 (Obsoletes rfc5738)
• 6856: Post Office Protocol Version 3 (POP3) Support for UTF-8 (Obsoletes rfc5721)
• 7162: IMAP Extensions: Quick Flag Changes Resynchronization (CONDSTORE) and Quick Mailbox Resynchronization (QRESYNC) (Obsoletes rfc4551, rfc5162) (Updates rfc2683)
• 7377: IMAP4 Multimailbox SEARCH Extension (Obsoletes rfc6237) (Updates rfc4466)
• 7628: A Set of Simple Authentication and Security Layer (SASL) Mechanisms for OAuth
• 7677: SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple Authentication and Security Layer (SASL) Mechanisms (Updates rfc5802)
• 7888: IMAP4 Non-synchronizing Literals (Obsoletes rfc2088)
• 7889: The IMAP APPENDLIMIT Extension
• 8437: IMAP UNAUTHENTICATE Extension for Connection Reuse (Updates rfc3501)
• 8438: IMAP Extension for STATUS=SIZE
• 8440: IMAP4 Extension for Returning MYRIGHTS Information in Extended LIST
• 8457: IMAP "$Important" Keyword and "\Important" Special-Use Attribute
• 8474: IMAP Extension for Object Identifiers
• 8508: IMAP REPLACE Extension (Updates rfc3501)
• 8514: Internet Message Access Protocol (IMAP) - SAVEDATE Extension
• 8689: SMTP Require TLS Option
• 8970: IMAP4 Extension: Message Preview Generation
• 9051: Internet Message Access Protocol (IMAP) - Version 4rev2
• 9208: IMAP QUOTA Extension (Obsoletes rfc2087)
• 9394: IMAP PARTIAL Extension for Paged SEARCH and FETCH