| 821 | Simple Mail Transfer ProtocolJ. Postel · obsoleted by RFC 2821 | Internet Standard | August 1982 |
| 822 | STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGESD. Crocker · obsoleted by RFC 2822 | Internet Standard | August 1982 |
| 937 | Post Office Protocol: Version 2M. Butler, J. Postel, D. Chase, J. Goldberger, J.K. Reynolds | Historic | February 1985 |
| 959 | File Transfer ProtocolJ. Postel, J. Reynolds | Internet Standard | October 1985 |
| 974 | Mail routing and the domain systemC. Partridge · obsoleted by RFC 2821 | Historic | January 1986 |
| 1035 | Domain names - implementation and specificationP. Mockapetris | Internet Standard | November 1987 |
| 1047 | Duplicate messages and SMTPC. Partridge | Unknown | February 1988 |
| 1056 | PCMAIL: A distributed mail system for personal computersM.L. Lambert | Informational | June 1988 |
| 1123 | Requirements for Internet Hosts - Application and SupportR. Braden, Ed. | Internet Standard | October 1989 |
| 1176 | Interactive Mail Access Protocol: Version 2M.R. Crispin | Experimental | August 1990 |
| 1652 | SMTP Service Extension for 8bit-MIMEtransportJ. Klensin, N. Freed, M. Rose, E. Stefferud, D. Crocker · obsoleted by RFC 6152 | Draft Standard | July 1994 |
| 1847 | Security Multiparts for MIME: Multipart/Signed and Multipart/EncryptedJ. Galvin, S. Murphy, S. Crocker, N. Freed | Proposed Standard | October 1995 |
| 1869 | SMTP Service ExtensionsJ. Klensin, N. Freed, M. Rose, E. Stefferud, D. Crocker · obsoleted by RFC 2821 | Internet Standard | November 1995 |
| 1870 | SMTP Service Extension for Message Size DeclarationJ. Klensin, N. Freed, K. Moore | Internet Standard | November 1995 |
| 1939 | Post Office Protocol - Version 3J. Myers, M. Rose | Internet Standard | May 1996 |
| 1985 | SMTP Service Extension for Remote Message Queue StartingJ. De Winter | Proposed Standard | August 1996 |
| 2045 | Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message BodiesN. Freed, N. Borenstein | Draft Standard | November 1996 |
| 2047 | MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII TextK. Moore | Draft Standard | November 1996 |
| 2119 | Key words for use in RFCs to Indicate Requirement LevelsS. Bradner | Best Current Practice | March 1997 |
| 2156 | MIXER (Mime Internet X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIMES. Kille | Proposed Standard | January 1998 |
| 2181 | Clarifications to the DNS SpecificationR. Elz, R. Bush | Proposed Standard | July 1997 |
| 2231 | MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and ContinuationsN. Freed, K. Moore | Proposed Standard | November 1997 |
| 2821 | Simple Mail Transfer ProtocolJ. Klensin, Ed. · obsoleted by RFC 5321 | Proposed Standard | April 2001 |
| 2920 | SMTP Service Extension for Command PipeliningN. Freed | Internet Standard | September 2000 |
| 2979 | Behavior of and Requirements for Internet FirewallsN. Freed | Informational | October 2000 |
| 3030 | SMTP Service Extensions for Transmission of Large and Binary MIME MessagesG. Vaudreuil | Proposed Standard | December 2000 |
| 3461 | Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)K. Moore | Draft Standard | January 2003 |
| 3463 | Enhanced Mail System Status CodesG. Vaudreuil | Draft Standard | January 2003 |
| 3464 | An Extensible Message Format for Delivery Status NotificationsK. Moore, G. Vaudreuil | Draft Standard | January 2003 |
| 3501 | INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1M. Crispin · obsoleted by RFC 9051 | Proposed Standard | March 2003 |
| 3798 | Message Disposition NotificationT. Hansen, Ed., G. Vaudreuil, Ed. · obsoleted by RFC 8098 | Draft Standard | May 2004 |
| 3848 | ESMTP and LMTP Transmission Types RegistrationC. Newman | Draft Standard | July 2004 |
| 3851 | Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message SpecificationB. Ramsdell, Ed. · obsoleted by RFC 5751 | Proposed Standard | July 2004 |
| 3864 | Registration Procedures for Message Header FieldsG. Klyne, M. Nottingham, J. Mogul | Best Current Practice | September 2004 |
| 3974 | SMTP Operational Experience in Mixed IPv4/v6 EnvironmentsM. Nakamura, J. Hagino | Informational | January 2005 |
| 4291 | IP Version 6 Addressing ArchitectureR. Hinden, S. Deering | Draft Standard | February 2006 |
| 4408 | Sender Policy Framework (SPF) for Authorizing Use of Domains in E-Mail, Version 1M. Wong, W. Schlitt · obsoleted by RFC 7208 | Experimental | April 2006 |
| 4409 | Message Submission for MailR. Gellens, J. Klensin · obsoleted by RFC 6409 | Draft Standard | April 2006 |
| 4686 | Analysis of Threats Motivating DomainKeys Identified Mail (DKIM)J. Fenton | Informational | September 2006 |
| 4871 | DomainKeys Identified Mail (DKIM) SignaturesE. Allman, J. Callas, M. Delany, M. Libbey, J. Fenton, M. Thomas · obsoleted by RFC 6376 | Proposed Standard | May 2007 |
| 4880 | OpenPGP Message FormatJ. Callas, L. Donnerhacke, H. Finney, D. Shaw, R. Thayer · obsoleted by RFC 9580 | Proposed Standard | November 2007 |
| 5234 | Augmented BNF for Syntax Specifications: ABNFD. Crocker, Ed., P. Overell | Internet Standard | January 2008 |
| 5248 | A Registry for SMTP Enhanced Mail System Status CodesT. Hansen, J. Klensin | Best Current Practice | June 2008 |
| 5322 | Internet Message FormatP. Resnick, Ed. | Draft Standard | October 2008 |