| 822 | STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGESD. Crocker · obsoleted by RFC 2822 | Internet Standard | August 1982 |
| 1845 | SMTP Service Extension for Checkpoint/RestartD. Crocker, N. Freed, A. Cargille | Experimental | September 1995 |
| 1870 | SMTP Service Extension for Message Size DeclarationJ. Klensin, N. Freed, K. Moore | Internet Standard | November 1995 |
| 2033 | Local Mail Transfer ProtocolJ. Myers | Informational | October 1996 |
| 2034 | SMTP Service Extension for Returning Enhanced Error CodesN. Freed | Proposed Standard | October 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 |
| 2205 | Resource ReSerVation Protocol (RSVP) -- Version 1 Functional SpecificationR. Braden, Ed., L. Zhang, S. Berson, S. Herzog, S. Jamin | Proposed Standard | September 1997 |
| 2474 | Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 HeadersK. Nichols, S. Blake, F. Baker, D. Black | Proposed Standard | December 1998 |
| 2852 | Deliver By SMTP Service ExtensionD. Newman | Proposed Standard | June 2000 |
| 3207 | SMTP Service Extension for Secure SMTP over Transport Layer SecurityP. Hoffman | Proposed Standard | February 2002 |
| 3461 | Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)K. Moore | Draft Standard | January 2003 |
| 4125 | Maximum Allocation Bandwidth Constraints Model for Diffserv-aware MPLS Traffic EngineeringF. Le Faucheur, W. Lai | Experimental | June 2005 |
| 4127 | Russian Dolls Bandwidth Constraints Model for Diffserv-aware MPLS Traffic EngineeringF. Le Faucheur, Ed. | Experimental | June 2005 |
| 4190 | Framework for Supporting Emergency Telecommunications Service (ETS) in IP TelephonyK. Carlberg, I. Brown, C. Beard | Informational | November 2005 |
| 4412 | Communications Resource Priority for the Session Initiation Protocol (SIP)H. Schulzrinne, J. Polk | Proposed Standard | February 2006 |
| 4422 | Simple Authentication and Security Layer (SASL)A. Melnikov, Ed., K. Zeilenga, Ed. | Proposed Standard | June 2006 |
| 5226 | Guidelines for Writing an IANA Considerations Section in RFCsT. Narten, H. Alvestrand · obsoleted by RFC 8126 | Best Current Practice | May 2008 |
| 5228 | Sieve: An Email Filtering LanguageP. Guenther, Ed., T. Showalter, Ed. | Proposed Standard | January 2008 |
| 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 |
| 5321 | Simple Mail Transfer ProtocolJ. Klensin | Draft Standard | October 2008 |
| 5322 | Internet Message FormatP. Resnick, Ed. | Draft Standard | October 2008 |
| 5598 | Internet Mail ArchitectureD. Crocker | Informational | July 2009 |
| 5741 | RFC Streams, Headers, and BoilerplatesL. Daigle, Ed., O. Kolkman, Ed., IAB · obsoleted by RFC 7841 | Informational | December 2009 |
| 6401 | RSVP Extensions for Admission PriorityF. Le Faucheur, J. Polk, K. Carlberg | Proposed Standard | October 2011 |
| 6409 | Message Submission for MailR. Gellens, J. Klensin | Internet Standard | November 2011 |
| 6647 | Email Greylisting: An Applicability Statement for SMTPM. Kucherawy, D. Crocker | Proposed Standard | June 2012 |