| 4021 | Registration of Mail and MIME Header FieldsG. Klyne, J. Palme | Proposed Standard | March 2005 |
| 3066 | Tags for the Identification of LanguagesH. Alvestrand · obsoleted by RFC 4646, RFC 4647 | Best Current Practice | January 2001 |
| 2626 | The Internet and the Millennium Problem (Year 2000)P. Nesser II | Informational | June 1999 |
| 2421 | Voice Profile for Internet Mail - version 2G. Vaudreuil, G. Parsons · obsoleted by RFC 3801 | Proposed Standard | September 1998 |
| 2252 | Lightweight Directory Access Protocol (v3): Attribute Syntax DefinitionsM. Wahl, A. Coulbeck, T. Howes, S. Kille · obsoleted by RFC 4510, RFC 4512, RFC 4517, RFC 4523 | Proposed Standard | December 1997 |
| 2249 | Mail Monitoring MIBN. Freed, S. Kille · obsoleted by RFC 2789 | Proposed Standard | January 1998 |
| 2248 | Network Services Monitoring MIBN. Freed, S. Kille · obsoleted by RFC 2788 | Proposed Standard | January 1998 |
| 2200 | Internet Official Protocol StandardsJ. Postel · obsoleted by RFC 2300 | Historic | June 1997 |
| 2164 | Use of an X.500/LDAP directory to support MIXER address mappingS. Kille | Proposed Standard | January 1998 |
| 2163 | Using the Internet DNS to Distribute MIXER Conformant Global Address Mapping (MCGAM)C. Allocchio | Proposed Standard | January 1998 |
| 2157 | Mapping between X.400 and RFC-822/MIME Message BodiesH. Alvestrand | Proposed Standard | January 1998 |
| 2156 | MIXER (Mime Internet X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIMES. Kille | Proposed Standard | January 1998 |
| 2076 | Common Internet Message HeadersJ. Palme | Informational | February 1997 |
| 2000 | Internet Official Protocol StandardsJ. Postel, Ed. · obsoleted by RFC 2200 | Historic | February 1997 |
| 1920 | Internet Official Protocol StandardsJ. Postel · obsoleted by RFC 2000 | Historic | March 1996 |
| 1911 | Voice Profile for Internet MailG. Vaudreuil · obsoleted by RFC 2421, RFC 2422, RFC 2423 | Experimental | February 1996 |
| 1899 | Request for Comments Summary RFC Numbers 1800-1899J. Elliott | Informational | January 1997 |
| 1880 | Internet Official Protocol StandardsJ. Postel, Ed. · obsoleted by RFC 1920 | Historic | November 1995 |
| 1838 | Use of the X.500 Directory to support mapping between X.400 and RFC 822 AddressesS. Kille · obsoleted by RFC 2164 | Experimental | August 1995 |
| 1836 | Representing the O/R Address hierarchy in the X.500 Directory Information TreeS. Kille · obsoleted by RFC 2294 | Experimental | August 1995 |
| 1800 | Internet Official Protocol StandardsJ. Postel, Ed. · obsoleted by RFC 1880 | Historic | July 1995 |
| 1780 | Internet Official Protocol StandardsJ. Postel, Ed. · obsoleted by RFC 1800 | Historic | March 1995 |
| 1778 | The String Representation of Standard Attribute SyntaxesT. Howes, S. Kille, W. Yeong, C. Robbins · obsoleted by RFC 3494 | Historic | March 1995 |
| 1766 | Tags for the Identification of LanguagesH. Alvestrand · obsoleted by RFC 3066, RFC 3282 | Proposed Standard | March 1995 |
| 1720 | Internet Official Protocol StandardsJ. Postel · obsoleted by RFC 1780 | Historic | November 1994 |
| 1713 | Tools for DNS debuggingA. Romao | Informational | November 1994 |
| 1711 | Classifications in E-mail RoutingJ. Houttuin | Informational | October 1994 |
| 1700 | Assigned NumbersJ. Reynolds, J. Postel · obsoleted by RFC 3232 | Historic | October 1994 |
| 1699 | Summary of 1600-1699J. Elliott | Informational | January 1997 |
| 1664 | Using the Internet DNS to Distribute RFC1327 Mail Address Mapping TablesC. Allocchio, A. Bonito, B. Cole, S. Giordano, R. Hagens · obsoleted by RFC 2163 | Experimental | August 1994 |
| 1649 | Operational Requirements for X.400 Management Domains in the GO-MHS CommunityR. Hagens, A. Hansen | Informational | July 1994 |
| 1648 | Postmaster Convention for X.400 OperationsA. Cargille | Historic | July 1994 |
| 1616 | X.400(1988) for the Academic and Research Community in EuropeRARE WG-MSG Task Force 88, E. Huizer, Ed., J. Romaguera, Ed. | Informational | May 1994 |
| 1615 | Migrating from X.400(84) to X.400(88)J. Houttuin, J. Craigie | Informational | May 1994 |
| 1599 | Summary of 1500-1599M. Kennedy | Informational | January 1997 |
| 1566 | Mail Monitoring MIBS. Kille, N. Freed · obsoleted by RFC 2249, RFC 2789 | Proposed Standard | January 1994 |
| 1565 | Network Services Monitoring MIBS. Kille, N. Freed · obsoleted by RFC 2248 | Proposed Standard | January 1994 |
| 1530 | Principles of Operation for the TPC.INT Subdomain: General Principles and PolicyC. Malamud, M. Rose | Informational | October 1993 |
| 1506 | A Tutorial on Gatewaying between X.400 and Internet MailJ. Houttuin | Informational | August 1993 |
| 1499 | Summary of 1400-1499J. Elliott | Informational | January 1997 |
| 1496 | Rules for downgrading messages from X.400/88 to X.400/84 when MIME content-types are present in the messagesH. Alvestrand, J. Romaguera, K. Jordan | Historic | August 1993 |
| 1495 | Mapping between X.400 and RFC-822 Message BodiesH. Alvestrand, S. Kille, R. Miles, M. Rose, S. Thompson · obsoleted by RFC 2156 | Proposed Standard | August 1993 |
| 1494 | Equivalences between 1988 X.400 and RFC-822 Message BodiesH. Alvestrand, S. Thompson | Historic | August 1993 |
| 1488 | The X.500 String Representation of Standard Attribute SyntaxesT. Howes, S. Kille, W. Yeong, C. Robbins · obsoleted by RFC 1778 | Proposed Standard | July 1993 |
| 1465 | Routing Coordination for X.400 MHS Services Within a Multi Protocol / Multi Network Environment Table Format V3 for Static RoutingD. Eppenberger | Experimental | May 1993 |
| 1405 | Mapping between X.400(1984/1988) and Mail-11 (DECnet mail)C. Allocchio · obsoleted by RFC 2162 | Experimental | January 1993 |
| 1360 | IAB Official Protocol StandardsJ. Postel · obsoleted by RFC 1410 | Historic | September 1992 |
| 1330 | Recommendations for the Phase I Deployment of OSI Directory Services (X.500) and OSI Message Handling Services (X.400) within the ESNET CommunityESCC X.500/X.400 Task Force, ESnet Site Coordinating Comittee (ESCC), Energy Sciences Network (ESnet) | Informational | May 1992 |
| 1328 | X.400 1988 to 1984 downgradingS. Hardcastle-Kille | Historic | May 1992 |