| 9580 | OpenPGPP. Wouters, Ed., D. Huigens, J. Winter, Y. Niibe | Proposed Standard | July 2024 |
| 5585 | DomainKeys Identified Mail (DKIM) Service OverviewT. Hansen, D. Crocker, P. Hallam-Baker | Informational | July 2009 |
| 4880 | OpenPGP Message FormatJ. Callas, L. Donnerhacke, H. Finney, D. Shaw, R. Thayer · obsoleted by RFC 9580 | Proposed Standard | November 2007 |
| 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 |
| 4716 | The Secure Shell (SSH) Public Key File FormatJ. Galbraith, R. Thayer | Informational | November 2006 |
| 4707 | Netnews Administration System (NAS)P. Grau, V. Heinau, H. Schlichting, R. Schuettler | Experimental | October 2006 |
| 4648 | The Base16, Base32, and Base64 Data EncodingsS. Josefsson | Proposed Standard | October 2006 |
| 4501 | Domain Name System Uniform Resource IdentifiersS. Josefsson | Proposed Standard | May 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 |
| 4398 | Storing Certificates in the Domain Name System (DNS)S. Josefsson | Proposed Standard | March 2006 |
| 4387 | Internet X.509 Public Key Infrastructure Operational Protocols: Certificate Store Access via HTTPP. Gutmann, Ed. | Proposed Standard | February 2006 |
| 4253 | The Secure Shell (SSH) Transport Layer ProtocolT. Ylonen, C. Lonvick, Ed. | Proposed Standard | January 2006 |
| 4230 | RSVP Security PropertiesH. Tschofenig, R. Graveman | Informational | December 2005 |
| 4212 | Alternative Certificate Formats for the Public-Key Infrastructure Using X.509 (PKIX) Certificate Management ProtocolsM. Blinov, C. Adams | Informational | October 2005 |
| 4161 | Guidelines for Optional Services for Internet Fax GatewaysK. Mimura, K. Yokoyama, T. Satoh, K. Watanabe, C. Kanaide | Informational | September 2005 |
| 4160 | Internet Fax Gateway RequirementsK. Mimura, K. Yokoyama, T. Satoh, C. Kanaide, C. Allocchio | Informational | September 2005 |
| 4086 | Randomness Requirements for SecurityD. Eastlake 3rd, J. Schiller, S. Crocker | Best Current Practice | June 2005 |
| 4027 | Domain Name System Media TypesS. Josefsson | Informational | May 2005 |
| 3965 | A Simple Mode of Facsimile Using Internet MailK. Toyoda, H. Ohno, J. Murai, D. Wing | Draft Standard | December 2004 |
| 3862 | Common Presence and Instant Messaging (CPIM): Message FormatG. Klyne, D. Atkins | Proposed Standard | August 2004 |
| 3819 | Advice for Internet Subnetwork DesignersP. Karn, Ed., C. Bormann, G. Fairhurst, D. Grossman, R. Ludwig, J. Mahdavi, G. Montenegro, J. Touch, L. Wood | Best Current Practice | July 2004 |
| 3792 | Survey of IPv4 Addresses in Currently Deployed IETF Security Area Standards Track and Experimental DocumentsP. Nesser, II, A. Bergstrom, Ed. | Informational | June 2004 |
| 3676 | The Text/Plain Format and DelSp ParametersR. Gellens | Proposed Standard | February 2004 |
| 3548 | The Base16, Base32, and Base64 Data EncodingsS. Josefsson, Ed. · obsoleted by RFC 4648 | Informational | July 2003 |
| 3520 | Session Authorization Policy ElementL-N. Hamer, B. Gage, B. Kosinski, H. Shieh | Proposed Standard | April 2003 |
| 3335 | MIME-based Secure Peer-to-Peer Business Data Interchange over the InternetT. Harding, R. Drummond, C. Shih | Proposed Standard | September 2002 |
| 3275 | (Extensible Markup Language) XML-Signature Syntax and ProcessingD. Eastlake 3rd, J. Reagle, D. Solo | Draft Standard | March 2002 |
| 3157 | Securely Available Credentials - RequirementsA. Arsenault, S. Farrell | Informational | August 2001 |
| 3156 | MIME Security with OpenPGPM. Elkins, D. Del Torto, R. Levien, T. Roessler | Proposed Standard | August 2001 |
| 2974 | Session Announcement ProtocolM. Handley, C. Perkins, E. Whelan | Experimental | October 2000 |
| 2821 | Simple Mail Transfer ProtocolJ. Klensin, Ed. · obsoleted by RFC 5321 | Proposed Standard | April 2001 |
| 2538 | Storing Certificates in the Domain Name System (DNS)D. Eastlake 3rd, O. Gudmundsson · obsoleted by RFC 4398 | Proposed Standard | March 1999 |