| 821 | Simple Mail Transfer ProtocolJ. Postel · obsoleted by RFC 2821 | Internet Standard | August 1982 |
| 1123 | Requirements for Internet Hosts - Application and SupportR. Braden, Ed. | Internet Standard | October 1989 |
| 1939 | Post Office Protocol - Version 3J. Myers, M. Rose | Internet Standard | May 1996 |
| 2045 | Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message BodiesN. Freed, N. Borenstein | Draft Standard | November 1996 |
| 2046 | Multipurpose Internet Mail Extensions (MIME) Part Two: Media TypesN. 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 |
| 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 |
| 3156 | MIME Security with OpenPGPM. Elkins, D. Del Torto, R. Levien, T. Roessler | Proposed Standard | August 2001 |
| 3461 | Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)K. Moore | Draft Standard | January 2003 |
| 3464 | An Extensible Message Format for Delivery Status NotificationsK. Moore, G. Vaudreuil | Draft Standard | January 2003 |
| 3492 | Punycode: A Bootstring encoding of Unicode for Internationalized Domain Names in Applications (IDNA)A. Costello | Proposed Standard | March 2003 |
| 3501 | INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1M. Crispin · obsoleted by RFC 9051 | Proposed Standard | March 2003 |
| 3629 | UTF-8, a transformation format of ISO 10646F. Yergeau | Internet Standard | November 2003 |
| 3987 | Internationalized Resource Identifiers (IRIs)M. Duerst, M. Suignard | Proposed Standard | January 2005 |
| 4155 | The application/mbox Media TypeE. Hall | Informational | September 2005 |
| 4690 | Review and Recommendations for Internationalized Domain Names (IDNs)J. Klensin, P. Faltstrom, C. Karp, IAB | Informational | September 2006 |
| 4952 | Overview and Framework for Internationalized EmailJ. Klensin, Y. Ko · obsoleted by RFC 6530 | Informational | July 2007 |
| 5198 | Unicode Format for Network InterchangeJ. Klensin, M. Padlipsky | Proposed Standard | March 2008 |
| 5228 | Sieve: An Email Filtering LanguageP. Guenther, Ed., T. Showalter, Ed. | Proposed Standard | January 2008 |
| 5280 | Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) ProfileD. Cooper, S. Santesson, S. Farrell, S. Boeyen, R. Housley, W. Polk | Proposed Standard | May 2008 |
| 5321 | Simple Mail Transfer ProtocolJ. Klensin | Draft Standard | October 2008 |
| 5322 | Internet Message FormatP. Resnick, Ed. | Draft Standard | October 2008 |
| 5335 | Internationalized Email HeadersA. Yang, Ed. · obsoleted by RFC 6532 | Experimental | September 2008 |
| 5336 | SMTP Extension for Internationalized Email AddressesJ. Yao, Ed., W. Mao, Ed. · obsoleted by RFC 6531 | Experimental | September 2008 |
| 5337 | Internationalized Delivery Status and Disposition NotificationsC. Newman, A. Melnikov, Ed. · obsoleted by RFC 6533 | Experimental | September 2008 |
| 5504 | Downgrading Mechanism for Email Address InternationalizationK. Fujiwara, Ed., Y. Yoneya, Ed. · obsoleted by RFC 6530 | Experimental | March 2009 |
| 5721 | POP3 Support for UTF-8R. Gellens, C. Newman · obsoleted by RFC 6856 | Experimental | February 2010 |
| 5738 | IMAP Support for UTF-8P. Resnick, C. Newman · obsoleted by RFC 6855 | Experimental | March 2010 |
| 5741 | RFC Streams, Headers, and BoilerplatesL. Daigle, Ed., O. Kolkman, Ed., IAB · obsoleted by RFC 7841 | Informational | December 2009 |
| 5751 | Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message SpecificationB. Ramsdell, S. Turner · obsoleted by RFC 8551 | Proposed Standard | January 2010 |
| 5825 | Displaying Downgraded Messages for Email Address InternationalizationK. Fujiwara, B. Leiba · obsoleted by RFC 6530 | Experimental | April 2010 |
| 5863 | DomainKeys Identified Mail (DKIM) Development, Deployment, and OperationsT. Hansen, E. Siegel, P. Hallam-Baker, D. Crocker | Informational | May 2010 |
| 5890 | Internationalized Domain Names for Applications (IDNA): Definitions and Document FrameworkJ. Klensin | Proposed Standard | August 2010 |
| 5891 | Internationalized Domain Names in Applications (IDNA): ProtocolJ. Klensin | Proposed Standard | August 2010 |
| 5892 | The Unicode Code Points and Internationalized Domain Names for Applications (IDNA)P. Faltstrom, Ed. | Proposed Standard | August 2010 |
| 5893 | Right-to-Left Scripts for Internationalized Domain Names for Applications (IDNA)H. Alvestrand, Ed., C. Karp | Proposed Standard | August 2010 |
| 5894 | Internationalized Domain Names for Applications (IDNA): Background, Explanation, and RationaleJ. Klensin | Informational | August 2010 |
| 5983 | Mailing Lists and Internationalized Email AddressesR. Gellens · obsoleted by RFC 6783 | Experimental | October 2010 |
| 6055 | IAB Thoughts on Encodings for Internationalized Domain NamesD. Thaler, J. Klensin, S. Cheshire | Informational | February 2011 |
| 6068 | The 'mailto' URI SchemeM. Duerst, L. Masinter, J. Zawinski | Proposed Standard | October 2010 |
| 6152 | SMTP Service Extension for 8-bit MIME TransportJ. Klensin, N. Freed, M. Rose, D. Crocker, Ed. | Internet Standard | March 2011 |
| 6409 | Message Submission for MailR. Gellens, J. Klensin | Internet Standard | November 2011 |
| 6531 | SMTP Extension for Internationalized EmailJ. Yao, W. Mao | Proposed Standard | February 2012 |
| 6532 | Internationalized Email HeadersA. Yang, S. Steele, N. Freed | Proposed Standard | February 2012 |
| 6533 | Internationalized Delivery Status and Disposition NotificationsT. Hansen, Ed., C. Newman, A. Melnikov | Proposed Standard | February 2012 |