This file lists RFC's that are relevant for email, along with implementation status. "make" fetches the RFC's and adds references back to the source code where they are referenced. The protocol support page on the website is generated from this information as well. Each tab-separated row has: - RFC number - Support/implementation status - RFC status (e.g. Obs for obsolete) - RFC title If the support status column value starts with a minus, it isn't included on the protocol page on the website. Valid words for implementation status: - Yes, support is deemed complete - Partial, support is partial, more work can be done - Roadmap, no support, but it is planned - No, not supported and no plans - ?, implementation status unknown Also see IANA assignments, https://www.iana.org/protocols # Internet Message Format 822 Yes Obs Standard for ARPA Internet Text Messages 1847 No - Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted 2045 Yes - Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies 2046 Yes - Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types 2047 Yes - MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text 2049 - - Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples 2076 - - Common Internet Message Headers 2183 Yes - Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field 2231 Yes - MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations 3629 - - UTF-8, a transformation format of ISO 10646 3676 No - The Text/Plain Format and DelSp Parameters 5234 - - Augmented BNF for Syntax Specifications: ABNF 5322 Yes - Internet Message Format 5598 - - Internet Mail Architecture 6854 - - Update to Internet Message Format to Allow Group Syntax in the "From:" and "Sender:" Header Fields 7405 - - Case-Sensitive String Support in ABNF 9078 - - Reaction: Indicating Summary Reaction to a Message 9228 Yes - Delivered-To Email Header Field https://www.iana.org/assignments/message-headers/message-headers.xhtml # SMTP 821 Yes Obs (RFC 2821) SIMPLE MAIL TRANSFER PROTOCOL 2821 Yes Obs (RFC 5321) Simple Mail Transfer Protocol 5321 Yes - Simple Mail Transfer Protocol 1870 Yes - SMTP Service Extension for Message Size Declaration 1985 No - SMTP Service Extension for Remote Message Queue Starting 2034 Yes - SMTP Service Extension for Returning Enhanced Error Codes 2852 No - Deliver By SMTP Service Extension 2920 Yes - SMTP Service Extension for Command Pipelining 2505 - - Anti-Spam Recommendations for SMTP MTAs 3207 Yes - SMTP Service Extension for Secure SMTP over Transport Layer Security (STARTTLS) 3030 Roadmap - SMTP Service Extensions for Transmission of Large and Binary MIME Messages 3461 Roadmap - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 3462 - Obs (RFC 6522) The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages 3463 Yes - Enhanced Mail System Status Codes 3464 Yes - An Extensible Message Format for Delivery Status Notifications 3798 ? Obs (RFC 8098) Message Disposition Notification 3848 - - ESMTP and LMTP Transmission Types Registration 3865 No - A No Soliciting Simple Mail Transfer Protocol (SMTP) Service Extension 3885 No - SMTP Service Extension for Message Tracking 3974 - - SMTP Operational Experience in Mixed IPv4/v6 Environments 4409 - Obs (RFC 6409) Message Submission for Mail 4468 Roadmap - Message Submission BURL Extension 4865 Yes - SMTP Submission Service Extension for Future Message Release 4865-eid2040 -Yes - errata: Internet-style-date-time-UTC -> date-time from rfc 3339 4954 Yes - SMTP Service Extension for Authentication 5068 - - Email Submission Operations: Access and Accountability Requirements 5248 - - A Registry for SMTP Enhanced Mail System Status Codes 5335 - Obs (RFC 6532) Internationalized Email Headers 5336 - Obs (RFC 6531) SMTP Extension for Internationalized Email Addresses 5337 - Obs (RFC 6533) Internationalized Delivery Status and Disposition Notifications 5782 Yes - DNS Blacklists and Whitelists 6008 Yes - Authentication-Results Registration for Differentiating among Cryptographic Results 6152 Yes - SMTP Service Extension for 8-bit MIME Transport 6409 Yes - Message Submission for Mail 6522 Yes - The Multipart/Report Media Type for the Reporting of Mail System Administrative Messages 6530 Yes - Overview and Framework for Internationalized Email 6531 Yes - SMTP Extension for Internationalized Email 6532 Yes - Internationalized Email Headers 6533 Yes - Internationalized Delivery Status and Disposition Notifications 6647 Partial - Email Greylisting: An Applicability Statement for SMTP 6710 No - Simple Mail Transfer Protocol Extension for Message Transfer Priorities 6729 No - Indicating Email Handling States in Trace Fields 6857 No - Post-Delivery Message Downgrading for Internationalized Email Messages 7293 No - The Require-Recipient-Valid-Since Header Field and SMTP Service Extension 7372 Yes - Email Authentication Status Codes 7435 Yes - Opportunistic Security: Some Protection Most of the Time 7504 Yes - SMTP 521 and 556 Reply Codes 7505 Yes - A "Null MX" No Service Resource Record for Domains That Accept No Mail 8098 ? - Message Disposition Notification 8601 Yes - Message Header Field for Indicating Message Authentication Status 8689 Yes - SMTP Require TLS Option 8904 No - DNS Whitelist (DNSWL) Email Authentication Method Extension 9422 Yes - The LIMITS SMTP Service Extension # SPF 4408 Yes Obs (by RFC 7208) Sender Policy Framework (SPF) for Authorizing Use of Domains in E-Mail, Version 1 6652 ? - Sender Policy Framework (SPF) Authentication Failure Reporting Using the Abuse Reporting Format 7208 Yes - Sender Policy Framework (SPF) for Authorizing Use of Domains in Email, Version 1 7208-eid5436 - - errata: header-field FWS 7208-eid6721 - - errata: corrected smtp example response 7208-eid4751 - - errata (not verified): ptr mechanism 7208-eid5227 - - errata (not verified): ptr lookup order 7208-eid6595 - - errata (not verified): 2 void lookups vs exists 7208-eid6216 - - errata (not verified): ptr in multiple requirements example from appendix A.4 # DKIM 6376 Yes - DomainKeys Identified Mail (DKIM) Signatures 6376-eid4810 - - errata: q= qp-hdr-value 6376-eid5070 - - errata: tag-spec 4686 - - Analysis of Threats Motivating DomainKeys Identified Mail (DKIM) 4871 Yes Obs (RFC 6376) DomainKeys Identified Mail (DKIM) Signatures 5016 -Yes - Requirements for a DomainKeys Identified Mail (DKIM) Signing Practices Protocol 5585 -Yes - DomainKeys Identified Mail (DKIM) Service Overview 5672 -Yes Obs (by RFC 6376) DomainKeys Identified Mail (DKIM) Signatures -- Update 5863 -Yes - DomainKeys Identified Mail (DKIM) Development, Deployment, and Operations 6377 ? - DomainKeys Identified Mail (DKIM) and Mailing Lists 8032 - - Edwards-Curve Digital Signature Algorithm (EdDSA) 8301 Yes - Cryptographic Algorithm and Key Usage Update to DomainKeys Identified Mail (DKIM) 8463 Yes - A New Cryptographic Signature Method for DomainKeys Identified Mail (DKIM) # DMARC 7489 Yes - Domain-based Message Authentication, Reporting, and Conformance (DMARC) 7489-eid5440 - - errata: valid dmarc records with(out) semicolon 7489-eid6729 - - errata (not verified): publicsuffix list only for ICANN DOMAINS 7960 Yes - Interoperability Issues between Domain-based Message Authentication, Reporting, and Conformance (DMARC) and Indirect Email Flows 9091 Roadmap - Experimental Domain-Based Message Authentication, Reporting, and Conformance (DMARC) Extension for Public Suffix Domains # ARC 8617 Roadmap - The Authenticated Received Chain (ARC) Protocol # DANE 6394 -Yes - Use Cases and Requirements for DNS-Based Authentication of Named Entities (DANE) 6698 Yes - The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA 7218 -Yes - Adding Acronyms to Simplify Conversations about DNS-Based Authentication of Named Entities (DANE) 7671 -Yes - The DNS-Based Authentication of Named Entities (DANE) Protocol: Updates and Operational Guidance 7672 Yes - SMTP Security via Opportunistic DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) 7673 Roadmap - Using DNS-Based Authentication of Named Entities (DANE) TLSA Records with SRV Records 7929 No - DNS-Based Authentication of Named Entities (DANE) Bindings for OpenPGP 8162 No - Using Secure DNS to Associate Certificates with Domain Names for S/MIME # MTA-STS 8461 Yes - SMTP MTA Strict Transport Security (MTA-STS) # TLS Reporting 8460 Yes - SMTP TLS Reporting 8460-eid6241 - - Wrong example for JSON field "mx-host". # ARF 5965 Roadmap - An Extensible Format for Email Feedback Reports 6650 Roadmap - Creation and Use of Email Feedback Reports: An Applicability Statement for the Abuse Reporting Format (ARF) 6591 ? - Authentication Failure Reporting Using the Abuse Reporting Format 6692 Roadmap - Source Ports in Abuse Reporting Format (ARF) Reports 9477 Roadmap - Complaint Feedback Loop Address Header # IMAP 1730 Yes Obs (RFC 2060) INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4 2060 Yes Obs (RFC 3501) INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1 3501 Yes Obs (RFC 9051) INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1 9051 Yes - Internet Message Access Protocol (IMAP) - Version 4rev2 1733 -Yes - DISTRIBUTED ELECTRONIC MAIL MODELS IN IMAP4 2087 Roadmap - IMAP4 QUOTA extension 2088 - Obs (RFC 7888) IMAP4 non-synchronizing literals 2152 Yes - UTF-7 A Mail-Safe Transformation Format of Unicode 2177 Yes - IMAP4 IDLE command 2180 Yes - IMAP4 Multi-Accessed Mailbox Practice 2193 No - IMAP4 Mailbox Referrals 2342 Yes - IMAP4 Namespace 2683 Yes - IMAP4 Implementation Recommendations 2971 Yes - IMAP4 ID extension 3348 Yes Obs (RFC 5258) The Internet Message Action Protocol (IMAP4) Child Mailbox Extension 3502 Roadmap - Internet Message Access Protocol (IMAP) - MULTIAPPEND Extension 3503 ? - Message Disposition Notification (MDN) profile for Internet Message Access Protocol (IMAP) 3516 Yes - IMAP4 Binary Content Extension 3691 Yes - Internet Message Access Protocol (IMAP) UNSELECT command 4314 Roadmap - IMAP4 Access Control List (ACL) Extension 4315 Yes - Internet Message Access Protocol (IMAP) - UIDPLUS extension 4466 -Yes - Collected Extensions to IMAP4 ABNF 4467 Roadmap - Internet Message Access Protocol (IMAP) - URLAUTH Extension 4469 Roadmap - Internet Message Access Protocol (IMAP) CATENATE Extension 4549 -Yes - Synchronization Operations for Disconnected IMAP4 Clients 4551 Yes Obs (RFC 7162) IMAP Extension for Conditional STORE Operation or Quick Flag Changes Resynchronization 4731 Yes - IMAP4 Extension to SEARCH Command for Controlling What Kind of Information Is Returned 4959 Yes - IMAP Extension for Simple Authentication and Security Layer (SASL) Initial Client Response 4978 Roadmap - The IMAP COMPRESS Extension 5032 Roadmap - WITHIN Search Extension to the IMAP Protocol 5092 Roadmap - IMAP URL Scheme 5161 Yes - The IMAP ENABLE Extension 5162 Yes Obs (RFC 7162) IMAP4 Extensions for Quick Mailbox Resynchronization 5182 Yes - IMAP Extension for Referencing the Last SEARCH Result 5255 No - Internet Message Access Protocol Internationalization 5256 Roadmap - Internet Message Access Protocol - SORT and THREAD Extensions 5257 No - Internet Message Access Protocol - ANNOTATE Extension 5258 Yes - Internet Message Access Protocol version 4 - LIST Command Extensions 5259 No - Internet Message Access Protocol - CONVERT Extension 5267 Roadmap - Contexts for IMAP4 5464 Roadmap - The IMAP METADATA Extension 5465 Roadmap - The IMAP NOTIFY Extension 5466 Roadmap - IMAP4 Extension for Named Searches (Filters) 5524 No - Extended URLFETCH for Binary and Converted Parts 5530 Yes - IMAP Response Codes 5738 Partial Obs (RFC 6855) IMAP Support for UTF-8 5788 -Yes - IMAP4 Keyword Registry 5819 Yes - IMAP4 Extension for Returning STATUS Information in Extended LIST 5957 Roadmap - Display-Based Address Sorting for the IMAP4 SORT Extension 6154 Yes - IMAP LIST Extension for Special-Use Mailboxes 6203 No - IMAP4 Extension for Fuzzy Search 6237 Roadmap Obs (RFC 7377) IMAP4 Multimailbox SEARCH Extension 6851 Yes - Internet Message Access Protocol (IMAP) - MOVE Extension 6855 Yes - IMAP Support for UTF-8 6858 No - Simplified POP and IMAP Downgrading for Internationalized Email 7162 Yes - IMAP Extensions: Quick Flag Changes Resynchronization (CONDSTORE) and Quick Mailbox Resynchronization (QRESYNC) 7162-eid5055 - - errata: space after untagged OK 7377 Roadmap - IMAP4 Multimailbox SEARCH Extension 7888 Yes - IMAP4 Non-synchronizing Literals 7889 Yes - The IMAP APPENDLIMIT Extension 8437 Roadmap - IMAP UNAUTHENTICATE Extension for Connection Reuse 8438 Yes - IMAP Extension for STATUS=SIZE 8440 ? - IMAP4 Extension for Returning MYRIGHTS Information in Extended LIST 8457 Roadmap - IMAP "$Important" Keyword and "\Important" Special-Use Attribute 8474 Roadmap - IMAP Extension for Object Identifiers 8508 Roadmap - IMAP REPLACE Extension 8514 Roadmap - Internet Message Access Protocol (IMAP) - SAVEDATE Extension 8970 Roadmap - IMAP4 Extension: Message Preview Generation 9208 Partial - IMAP QUOTA Extension 9394 Roadmap - IMAP PARTIAL Extension for Paged SEARCH and FETCH 5198 -? - Unicode Format for Network Interchange # Lemonade profile 4550 -? Obs (RFC 5550) Internet Email to Support Diverse Service Environments (Lemonade) Profile 5383 -? - Deployment Considerations for Lemonade-Compliant Mobile Email 5423 -? - Internet Message Store Events 5442 -? - LEMONADE Architecture - Supporting Open Mobile Alliance (OMA) Mobile Email (MEM) Using Internet Mail 5550 -? - The Internet Email to Support Diverse Service Environments (Lemonade) Profile 5551 -? - Lemonade Notifications Architecture # Mailing list and automated responses 2369 ? - The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields 2919 ? - List-Id: A Structured Field and Namespace for the Identification of Mailing Lists 3834 ? - Recommendations for Automatic Responses to Electronic Mail 8058 ? - Signaling One-Click Functionality for List Email Headers # Sieve 3028 Roadmap Obs (RFC 5228) Sieve: A Mail Filtering Language 5228 Roadmap - Sieve: An Email Filtering Language 5804 Roadmap - A Protocol for Remotely Managing Sieve Scripts 3894 No - Sieve Extension: Copying Without Side Effects 5173 No - Sieve Email Filtering: Body Extension 5183 Roadmap - Sieve Email Filtering: Environment Extension 5229 Roadmap - Sieve Email Filtering: Variables Extension 5230 Roadmap - Sieve Email Filtering: Vacation Extension 5231 Roadmap - Sieve Email Filtering: Relational Extension 5232 Roadmap - Sieve Email Filtering: Imap4flags Extension 5233 Roadmap - Sieve Email Filtering: Subaddress Extension 5235 No - Sieve Email Filtering: Spamtest and Virustest Extensions 5260 No - Sieve Email Filtering: Date and Index Extensions 5293 No - Sieve Email Filtering: Editheader Extension 5429 Roadmap - Sieve Email Filtering: Reject and Extended Reject Extensions 5435 No - Sieve Email Filtering: Extension for Notifications 5437 No - Sieve Notification Mechanism: Extensible Messaging and Presence Protocol (XMPP) 5463 Roadmap - Sieve Email Filtering: Ihave Extension 5490 No - The Sieve Mail-Filtering Language -- Extensions for Checking Mailbox Status and Accessing Mailbox Metadata 5703 No - Sieve Email Filtering: MIME Part Tests, Iteration, Extraction, Replacement, and Enclosure 5784 No - Sieve Email Filtering: Sieves and Display Directives in XML 6131 ? - Sieve Vacation Extension: "Seconds" Parameter 6558 No - Sieve Extension for Converting Messages before Delivery 6609 No - Sieve Email Filtering: Include Extension 6785 Roadmap - Support for Internet Message Access Protocol (IMAP) Events in Sieve 8579 Roadmap - Sieve Email Filtering: Delivering to Special-Use Mailboxes 8580 No - Sieve Extension: File Carbon Copy (FCC) 9042 No - Sieve Email Filtering: Delivery by MAILBOXID 3431 Roadmap Obs (RFC 5231) Relational Extension 3598 Roadmap Obs (RFC 5233) Subaddress Extension 3685 No Obs (RFC 5235) Spamtest and VirusTest Extensions Also see http://sieve.info/documents # JMAP 8620 Roadmap - The JSON Meta Application Protocol (JMAP) 8621 Roadmap - The JSON Meta Application Protocol (JMAP) for Mail 8887 Roadmap - A JSON Meta Application Protocol (JMAP) Subprotocol for WebSocket 9007 ? - Handling Message Disposition Notification with the JSON Meta Application Protocol (JMAP) 9219 No - S/MIME Signature Verification Extension to the JSON Meta Application Protocol (JMAP) 9425 No - JSON Meta Application Protocol (JMAP) for Quotas See implementation guide, https://jmap.io/server.html # CalDAV/iCal 4791 Roadmap - Calendaring Extensions to WebDAV (CalDAV) 5689 Roadmap - Extended MKCOL for Web Distributed Authoring and Versioning (WebDAV) 6638 Roadmap - Scheduling Extensions to CalDAV 6764 Roadmap - Locating Services for Calendaring Extensions to WebDAV (CalDAV) and vCard Extensions to WebDAV (CardDAV) 7809 Roadmap - Calendaring Extensions to WebDAV (CalDAV): Time Zones by Reference 7953 Roadmap - Calendar Availability 5545 Roadmap - Internet Calendaring and Scheduling Core Object Specification (iCalendar) 5546 Roadmap - iCalendar Transport-Independent Interoperability Protocol (iTIP) 6047 Roadmap - iCalendar Message-Based Interoperability Protocol (iMIP) 6868 Roadmap - Parameter Value Encoding in iCalendar and vCard 7529 ? - Non-Gregorian Recurrence Rules in the Internet Calendaring and Scheduling Core Object Specification (iCalendar) 7986 ? - New Properties for iCalendar 9073 ? - Event Publishing Extensions to iCalendar 9074 ? - "VALARM" Extensions for iCalendar 9253 ? - Support for iCalendar Relationships 6321 ? - xCal: The XML Format for iCalendar 7265 ? - jCal: The JSON Format for iCalendar # CardDAV/vCard 6352 Roadmap - CardDAV: vCard Extensions to Web Distributed Authoring and Versioning (WebDAV) 2425 Roadmap - A MIME Content-Type for Directory Information 2426 ? - vCard MIME Directory Profile 6350 Roadmap - vCard Format Specification 6351 ? - xCard: vCard XML Representation 6473 ? - vCard KIND:application 6474 ? - vCard Format Extensions: Place of Birth, Place and Date of Death 6715 ? - vCard Format Extensions: Representing vCard Extensions Defined by the Open Mobile Alliance (OMA) Converged Address Book (CAB) Group 6869 ? - vCard KIND:device 7095 ? - jCard: The JSON Format for vCard # WebDAV 4918 Roadmap - HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) 3253 ? - Versioning Extensions to WebDAV (Web Distributed Authoring and Versioning) 3648 ? - Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol 3744 ? - Web Distributed Authoring and Versioning (WebDAV) Access Control Protocol 4437 ? - Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources 5323 ? - Web Distributed Authoring and Versioning (WebDAV) SEARCH 6578 ? - Collection Synchronization for Web Distributed Authoring and Versioning (WebDAV) # SASL 2104 - - HMAC: Keyed-Hashing for Message Authentication 2195 Yes - IMAP/POP AUTHorize Extension for Simple Challenge/Response 4013 Yes Obs (RFC 7613) SASLprep: Stringprep Profile for User Names and Passwords 4422 Yes - Simple Authentication and Security Layer (SASL) 4505 No - Anonymous Simple Authentication and Security Layer (SASL) Mechanism 4616 Yes - The PLAIN Simple Authentication and Security Layer (SASL) Mechanism 5802 Yes - Salted Challenge Response Authentication Mechanism (SCRAM) SASL and GSS-API Mechanisms 6331 -No - Moving DIGEST-MD5 to Historic 7613 Yes Obs (RFC 8265) Preparation, Enforcement, and Comparison of Internationalized Strings Representing Usernames and Passwords 7677 Yes - SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple Authentication and Security Layer (SASL) Mechanisms 8265 Yes - Preparation, Enforcement, and Comparison of Internationalized Strings Representing Usernames and Passwords # Internationalization 3492 Yes - Punycode: A Bootstring encoding of Unicode for Internationalized Domain Names in Applications (IDNA) 5890 Yes - Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework 5891 Yes - Internationalized Domain Names in Applications (IDNA): Protocol 5892 ? - The Unicode Code Points and Internationalized Domain Names for Applications (IDNA) 5893 ? - Right-to-Left Scripts for Internationalized Domain Names for Applications (IDNA) 5894 ? - Internationalized Domain Names for Applications (IDNA): Background, Explanation, and Rationale 8616 Yes - Email Authentication for Internationalized Mail # TLS 5056 Yes - On the Use of Channel Bindings to Secure Channels 5705 Yes - Keying Material Exporters for Transport Layer Security (TLS) 5929 Yes - Channel Bindings for TLS 6125 -? - Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS) 7250 -No - Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) 7525 -? - Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) 7627 -? - Transport Layer Security (TLS) Session Hash and Extended Master Secret Extension 8314 Yes - Cleartext Considered Obsolete: Use of Transport Layer Security (TLS) for Email Submission and Access 8446 Yes - The Transport Layer Security (TLS) Protocol Version 1.3 8996 Yes - Deprecating TLS 1.0 and TLS 1.1 8997 Yes - Deprecation of TLS 1.1 for Email Submission and Access 9266 Yes - Channel Bindings for TLS 1.3 # ACME 8555 Yes - Automatic Certificate Management Environment (ACME) 8737 Yes - Automated Certificate Management Environment (ACME) TLS Application-Layer Protocol Negotiation (ALPN) Challenge Extension # CAA 8659 Yes - DNS Certification Authority Authorization (CAA) Resource Record 8657 Yes - Certification Authority Authorization (CAA) Record Extensions for Account URI and Automatic Certificate Management Environment (ACME) Method Binding # Vouch by reference 5518 -? - Vouch By Reference # HTTP 2616 Yes Obs (RFC 7230) Hypertext Transfer Protocol -- HTTP/1.1 6455 Yes - The WebSocket Protocol 7230 Yes Obs (RFC 9110) Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing 9110 Yes - HTTP Semantics # More 3339 -? - Date and Time on the Internet: Timestamps 3986 -? - Uniform Resource Identifier (URI): Generic Syntax 5617 -? - (Historic) DomainKeys Identified Mail (DKIM) Author Domain Signing Practices (ADSP) 6068 -Yes - The 'mailto' URI Scheme 6186 -? - (not used in practice) Use of SRV Records for Locating Email Submission/Access Services 7817 -? - Updated Transport Layer Security (TLS) Server Identity Check Procedure for Email-Related Protocols # DNS 1034 -? - DOMAIN NAMES - CONCEPTS AND FACILITIES 1035 -? - DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION 1101 -? - DNS Encoding of Network Names and Other Types 1536 -? - Common DNS Implementation Errors and Suggested Fixes 2181 -? - Clarifications to the DNS Specification 2308 -? - Negative Caching of DNS Queries (DNS NCACHE) 2672 -? - (obsoleted by RFC 6672) Non-Terminal DNS Name Redirection 3226 -? - DNSSEC and IPv6 A6 aware server/resolver message size requirements 3363 -? - Representing Internet Protocol version 6 (IPv6) Addresses in the Domain Name System (DNS) 3596 -? - DNS Extensions to Support IP Version 6 3597 -? - Handling of Unknown DNS Resource Record (RR) Types 3833 -? - Threat Analysis of the Domain Name System (DNS) 4343 -? - Domain Name System (DNS) Case Insensitivity Clarification 4592 -? - The Role of Wildcards in the Domain Name System 5001 -? - DNS Name Server Identifier (NSID) Option 5452 -? - Measures for Making DNS More Resilient against Forged Answers 6604 -? - xNAME RCODE and Status Bits Clarification 6672 -? - DNAME Redirection in the DNS 6891 -? - Extension Mechanisms for DNS (EDNS(0)) 6895 -? - Domain Name System (DNS) IANA Considerations 7686 -? - The ".onion" Special-Use Domain Name 7766 -? - DNS Transport over TCP - Implementation Requirements 7828 -? - The edns-tcp-keepalive EDNS0 Option 7873 -? - Domain Name System (DNS) Cookies 8020 -? - NXDOMAIN: There Really Is Nothing Underneath 8482 -? - Providing Minimal-Sized Responses to DNS Queries That Have QTYPE=ANY 8490 -? - DNS Stateful Operations 8499 -? - DNS Terminology 8767 -? - Serving Stale Data to Improve DNS Resiliency 8914 -? - Extended DNS Errors 9018 -? - Interoperable Domain Name System (DNS) Server Cookies 9210 -? - DNS Transport over TCP - Operational Requirements # DNSSEC 3225 -? - Indicating Resolver Support of DNSSEC 3658 -? - Delegation Signer (DS) Resource Record (RR) 4033 -? - DNS Security Introduction and Requirements 4034 -? - Resource Records for the DNS Security Extensions 4035 -? - Protocol Modifications for the DNS Security Extensions 4470 -? - Minimally Covering NSEC Records and DNSSEC On-line Signing 4956 -? - DNS Security (DNSSEC) Opt-In 5155 -? - DNS Security (DNSSEC) Hashed Authenticated Denial of Existence 5702 -? - Use of SHA-2 Algorithms with RSA in DNSKEY and RRSIG Resource Records for DNSSEC 5933 -? - Use of GOST Signature Algorithms in DNSKEY and RRSIG Resource Records for DNSSEC 6014 -? - Cryptographic Algorithm Identifier Allocation for DNSSEC 6781 -? - DNSSEC Operational Practices, Version 2 6840 -? - Clarifications and Implementation Notes for DNS Security (DNSSEC) 7901 -? - CHAIN Query Requests in DNS 8198 -? - Aggressive Use of DNSSEC-Validated Cache 8624 -? - Algorithm Implementation Requirements and Usage Guidance for DNSSEC 8749 -? - Moving DNSSEC Lookaside Validation (DLV) to Historic Status 9077 -? - NSEC and NSEC3: TTLs and Aggressive Use 9157 -? - Revised IANA Considerations for DNSSEC 9276 -? - Guidance for NSEC3 Parameter Settings