Areas / Email

Email

SMTP, MIME, IMAP and message formats.

565 RFCs · 565 with AI ELI5 · 0 summaries · 0 index pages

With AI ELI5 565

RFC 6376 DKIM DomainKeys Identified Mail (DKIM) Signatures How a domain signs the email it sends, so receivers can check the mail really passed through it unchanged. RFC 2045 MIME Part One Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies How plain-text email learned to carry pictures, other alphabets and attachments. RFC 2046 MIME media types Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types How an email message says what each piece of it is, and how pieces nest inside one another. RFC 5228 Sieve Sieve: An Email Filtering Language A small, safe language for sorting incoming email by rules, with no loops, variables or shell access. RFC 3461 SMTP DSN Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) How an email sender can ask the mail system for a receipt, and say exactly when and how much to report back. RFC 2047 MIME Part 3 - Headers Multipurpose Internet Mail Extensions (MIME) Part Three: Message Header Extensions for Non-ASCII Text How non-ASCII text such as accented names and subjects is smuggled through email headers as plain printable ASCII. RFC 5322 Email Format Internet Message Format Defining the syntax of email messages - headers, body, addresses, and dates - the format behind every email you've ever sent or received. RFC 3463 Enhanced status codes Enhanced Mail System Status Codes A three-part number like 5.1.1 that says, in any language, why a mail message was or was not delivered. RFC 6409 Mail Submission Message Submission for Mail Why your mail program hands outgoing mail to a submission server on port 587 instead of dropping it into the open mail network. RFC 3464 DSN message format An Extensible Message Format for Delivery Status Notifications The standard, machine-readable format for the 'your message could not be delivered' notes mail servers send back. RFC 5321 SMTP Simple Mail Transfer Protocol The current standard for Internet email delivery, defining how billions of messages are routed and delivered every day. RFC 7208 SPF Sender Policy Framework (SPF) for Authorizing Use of Domains in Email, Version 1 How a domain publishes, in DNS, which servers may send its email, and how receivers check it. RFC 4466 IMAP ABNF extensions Collected Extensions to IMAP4 ABNF One place for the grammar of IMAP command extensions, plus a standard pattern for adding new options. RFC 2183 Content-Disposition Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field The mail header that tells a mail program whether to show a part now or offer it as an attachment. RFC 2595 IMAP/POP3 over TLS Using TLS with IMAP, POP3 and ACAP How mail clients upgrade an IMAP, POP3 or ACAP connection to TLS in place, and a PLAIN login for use inside it. RFC 2634 S/MIME Enhanced Security Enhanced Security Services for S/MIME Four optional add-ons for S/MIME email: signed receipts, security labels, secure mailing lists and signing-certificate binding. RFC 8620 JMAP The JSON Meta Application Protocol (JMAP) A generic JSON-over-HTTPS protocol for syncing mail, calendars and contacts, with batching, delta updates and push. RFC 3207 SMTP STARTTLS SMTP Service Extension for Secure SMTP over Transport Layer Security How an SMTP client and server upgrade a plain-text mail connection to one protected by TLS. RFC 5229 Sieve variables Sieve Email Filtering: Variables Extension Gives Sieve mail filters named variables, string substitution and a way to test the result. RFC 1870 SMTP SIZE SMTP Service Extension for Message Size Declaration Lets an email client announce a message's size up front so the server can refuse it before it is sent. RFC 2846 GSTN addressing in email GSTN Address Element Extensions in E-mail Services How to write telephone and fax numbers, subaddresses, names and postal details inside an e-mail address. RFC 3502 IMAP MULTIAPPEND Internet Message Access Protocol (IMAP) - MULTIAPPEND Extension Upload a whole batch of messages to an IMAP mailbox with one APPEND command, all or nothing. RFC 5965 ARF An Extensible Format for Email Feedback Reports A standard, machine-readable email format for telling another mail operator about spam, fraud, viruses and similar problems. RFC 4467 IMAP URLAUTH Internet Message Access Protocol (IMAP) - URLAUTH Extension IMAP URLs that carry their own authorization, so a client can hand out access to one message or part. RFC 6591 ARF Auth Failure Reports Authentication Failure Reporting Using the Abuse Reporting Format A standard report format for telling a sender why one of its messages failed DKIM or SPF checks. RFC 2156 MIXER MIXER (Mime Internet X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIME The rulebook for gateways that translate mail between X.400 and Internet RFC 822/MIME mail, covering addresses, headers and service elements. RFC 2920 SMTP pipelining SMTP Service Extension for Command Pipelining How an SMTP client may send several commands in one batch instead of waiting for a reply after each. RFC 8098 MDN Message Disposition Notification How email can ask for, and report back, what a recipient's mail program did with a message. RFC 3204 MIME media types for ISUP and QSIG Objects Two MIME types that let SIP messages carry telephone-network signaling untouched. RFC 5230 Sieve vacation Sieve Email Filtering: Vacation Extension How a Sieve mail filter can send an automatic 'I am away' reply without starting mail loops or spamming people. RFC 5804 ManageSieve A Protocol for Remotely Managing Sieve Scripts A line-based protocol for uploading, listing, activating and checking email filter scripts on a server you cannot log into. RFC 4954 SMTP AUTH SMTP Service Extension for Authentication How an SMTP client proves who it is to a mail server, using SASL mechanisms and a new AUTH command. RFC 5256 IMAP SORT/THREAD Internet Message Access Protocol - SORT and THREAD Extensions Let the IMAP server sort a mailbox and group replies into conversations, so the client does not have to download everything first. RFC 5092 IMAP URL IMAP URL Scheme How to write a link that points at an IMAP server, a mailbox, a search result or a single message. RFC 6152 SMTP 8BITMIME SMTP Service Extension for 8-bit MIME Transport How an SMTP server announces that it will accept 8-bit MIME message bodies, and how a client asks to send one. RFC 5267 IMAP Contexts Contexts for IMAP4 IMAP extensions that let a server push live changes to search and sort results and hand them out in windows. RFC 4731 IMAP SEARCH RETURN IMAP4 Extension to SEARCH Command for Controlling What Kind of Information Is Returned Lets an IMAP client ask SEARCH for just the first match, last match, a count or a compact list instead of every message number. RFC 6530 Internationalized Email Overview and Framework for Internationalized Email The framework for email addresses and headers written in the sender's own language and script, using UTF-8. RFC 8314 TLS for Email Cleartext Considered Obsolete: Use of Transport Layer Security (TLS) for Email Submission and Access Why mail clients and servers should use TLS from the first byte, and what that means for ports, DNS and certificates. RFC 2231 MIME Parameter Encoding MIME Parameter Value and Encoded Word Extensions How MIME parameters such as filenames can carry non-ASCII text, a language tag, and be split across several pieces. RFC 1847 MIME Security Multiparts Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted Two MIME wrappers that carry protected data and the control information needed to verify or unlock it. RFC 5435 Sieve Notify Sieve Email Filtering: Extension for Notifications A Sieve mail-filter action that pushes an instant notification when a message arrives, instead of making users poll. RFC 6186 SRV for Email Use of SRV Records for Locating Email Submission/Access Services Mail programs can find a domain's mail servers from just an email address, using DNS SRV records. RFC 4468 SMTP BURL Message Submission BURL Extension A BURL command that lets a mail submission server pull a message from an IMAP server instead of making the client upload it. RFC 4469 IMAP CATENATE Internet Message Access Protocol (IMAP) CATENATE Extension An IMAP extension that builds a new message on the server from new text plus pieces of messages already stored there. RFC 2387 multipart/related The MIME Multipart/Related Content-type One MIME mechanism for bundling a main document with the parts that only make sense together with it. RFC 4314 IMAP ACL IMAP4 Access Control List (ACL) Extension How an IMAP server describes who may do what to each mailbox, and how clients read and change those permissions. RFC 3801 VPIM Voice Profile for Internet Mail - version 2 (VPIMv2) A restricted profile of Internet mail that lets voice mail machines from different makers swap voice messages. RFC 2049 MIME Part 5 - Conformance Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples The checklist that says what a mail program must do to count as MIME-ready, plus the model behind MIME encoding. RFC 2449 POP3 Extensions POP3 Extension Mechanism How a POP3 server tells a mail client which optional commands and behaviors it offers. RFC 3458 Message-Context header Message Context for Internet Mail A mail header that hints whether a message is voice mail, a fax, a page or ordinary email. RFC 3459 Critical-Content Critical Content Multi-purpose Internet Mail Extensions (MIME) Parameter A Content-Disposition parameter that lets a sender mark which message parts must arrive and which may be dropped. RFC 3516 IMAP BINARY IMAP4 Binary Content Extension Lets an IMAP server decode attachments itself, so the client gets raw bytes instead of Base64 text. RFC 3834 Auto-Response to Email Recommendations for Automatic Responses to Electronic Mail Rules for vacation replies and other mail robots so they stay useful and never start mail loops. RFC 6532 Internationalized Email Headers Lets email headers and addresses use UTF-8 directly, with no encoded-word tricks. RFC 9051 IMAP4rev2 Internet Message Access Protocol (IMAP) - Version 4rev2 The current rules for reading and managing email that stays on a server, folded together from IMAP4rev1 and its popular extensions. RFC 5518 Vouch By Reference Vouch By Reference How a mail sender can name outside certifiers who will vouch for its domain, checked by receivers through a DNS lookup. RFC 9989 DMARC Domain-Based Message Authentication, Reporting, and Conformance (DMARC) How a domain owner tells receivers which email really comes from its name, what to do with the rest, and where to send reports. RFC 2195 CRAM-MD5 IMAP/POP AUTHorize Extension for Simple Challenge/Response A simple login handshake for IMAP mail that proves you know the password without sending it. RFC 6531 SMTP Internationalization SMTP Extension for Internationalized Email The SMTP extension that lets mail servers agree to carry non-ASCII addresses and UTF-8 headers. RFC 5617 DKIM ADSP DomainKeys Identified Mail (DKIM) Author Domain Signing Practices (ADSP) A DNS record that let a domain announce that it signs all its mail with DKIM, so receivers could judge unsigned messages. Now Historic. RFC 822 Mail message format STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES The 1982 standard for what an email message looks like: header fields, a blank line, then the body. RFC 5231 Sieve relational Sieve Email Filtering: Relational Extension Lets Sieve mail filters compare values with greater-than and less-than, and count headers or addresses. RFC 9991 DMARC failure reports Domain-Based Message Authentication, Reporting, and Conformance (DMARC) Failure Reporting Per-message DMARC failure reports that tell a domain owner exactly which mail failed authentication, and the privacy cost of sending them. RFC 7162 IMAP CONDSTORE QRESYNC IMAP Extensions: Quick Flag Changes Resynchronization (CONDSTORE) and Quick Mailbox Resynchronization (QRESYNC) How IMAP clients and servers track flag changes and expunged messages so a reconnecting client resyncs fast. RFC 1421 PEM Privacy Enhancement for Internet Electronic Mail: Part I: Message Encryption and Authentication Procedures How Privacy Enhanced Mail encrypts, signs and encodes an email message from sender to recipient. RFC 2015 MIME Security with PGP MIME Security with Pretty Good Privacy (PGP) How to wrap PGP-encrypted and PGP-signed data inside standard MIME email messages. RFC 4102 text/red Registration of the text/red MIME Sub-Type The registration that gives redundant real-time text its official MIME name, text/red. RFC 5598 Internet Mail Arch Internet Mail Architecture A shared vocabulary and map of the roles, identities and components that make Internet email work. RFC 5464 IMAP METADATA The IMAP METADATA Extension Sticky notes for IMAP: attach named annotations to a mailbox, or to the whole server. RFC 4315 IMAP UIDPLUS Internet Message Access Protocol (IMAP) - UIDPLUS extension Small IMAP additions that tell a client the UIDs of messages it just copied or appended, and let it expunge only chosen messages. RFC 2142 Mailbox Names Mailbox Names for Common Services, Roles and Functions The standard addresses, like postmaster and abuse, that every organization on the Internet should answer. RFC 3156 MIME OpenPGP MIME Security with OpenPGP How to wrap OpenPGP signatures and encryption inside MIME email using three content types. RFC 3191 GSTN Email Address Minimal GSTN address format in Internet Mail A minimal way to write a telephone number inside an email address, with a registered extension mechanism. RFC 3192 Fax Email Address Minimal FAX address format in Internet Mail How to write a fax machine's telephone number as the local part of an ordinary email address. RFC 6533 Internationalized DSNs Internationalized Delivery Status and Disposition Notifications How bounce messages and read receipts keep the original recipient address when it contains non-ASCII characters. RFC 9990 DMARC aggregate reports Domain-Based Message Authentication, Reporting, and Conformance (DMARC) Aggregate Reporting The XML daily summary that mail receivers send to a domain owner about who is sending mail in its name. RFC 2532 Extended Internet Fax Extended Facsimile Using Internet Mail Fax over ordinary email, with required delivery confirmation and optional higher-quality documents. RFC 2852 DELIVERBY Deliver By SMTP Service Extension How an email sender can ask a mail server to deliver by a deadline, and say what should happen if the deadline is missed. RFC 2077 MIME Model Type The Model Primary Content Type for Multipurpose Internet Mail Extensions A proposed new top-level MIME type, model, for 3D shapes, meshes and other structured models. RFC 2342 IMAP NAMESPACE IMAP4 Namespace A one-command way for an IMAP client to learn where a server keeps your mailboxes and everyone else's. RFC 1422 PEM keys Privacy Enhancement for Internet Electronic Mail: Part II: Certificate-Based Key Management A single worldwide certification hierarchy for the keys behind Privacy Enhanced Mail. RFC 1731 IMAP4 auth IMAP4 Authentication Mechanisms Three ways an IMAP4 client can prove who it is: Kerberos v4, GSSAPI and S/Key. RFC 2369 List-* headers The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields Standard List-* header fields that let mail programs show Subscribe, Unsubscribe and Help buttons for any mailing list. RFC 8621 JMAP for Mail The JSON Meta Application Protocol (JMAP) for Mail How a mail app reads, searches, organises and sends email over JMAP, with one JSON data model instead of IMAP and SMTP plumbing. RFC 1423 PEM algorithms Privacy Enhancement for Internet Electronic Mail: Part III: Algorithms, Modes, and Identifiers The list of ciphers, digests and key formats that Privacy Enhanced Mail was allowed to use, with the exact names and byte layouts. RFC 3965 Simple Mode IFax A Simple Mode of Facsimile Using Internet Mail How to send a fax as an ordinary email with a TIFF image attached, and how gateways bridge to phone-line fax machines. RFC 5550 Lemonade profile The Internet Email to Support Diverse Service Environments (Lemonade) Profile A checklist of IMAP, mail submission and Sieve extensions that lets phones and other constrained clients handle email cheaply. RFC 6068 mailto URI The 'mailto' URI Scheme How a link can open a new email, with the recipient, subject and body already filled in. RFC 5161 IMAP ENABLE The IMAP ENABLE Extension How an IMAP client tells the server which opt-in extensions it understands. RFC 5258 IMAP LIST Extensions Internet Message Access Protocol version 4 - LIST Command Extensions One extensible IMAP LIST command, with options, so every new way of listing mailboxes stops needing its own command. RFC 5465 IMAP NOTIFY The IMAP NOTIFY Extension How an IMAP client tells the server exactly which mailbox changes to push, without keeping a connection open per mailbox. RFC 2034 SMTP Enhanced Errors SMTP Service Extension for Returning Enhanced Error Codes Lets an SMTP server put machine-readable status codes like 5.1.1 in front of its reply text. RFC 2177 IMAP IDLE IMAP4 IDLE command A command that lets an IMAP client wait while the server pushes mailbox updates in real time. RFC 2683 IMAP4 Impl. Tips IMAP4 Implementation Recommendations Practical advice for IMAP4 client and server authors on the traps that break interoperability. RFC 3335 MIME business data (EDI) MIME-based Secure Peer-to-Peer Business Data Interchange over the Internet How businesses can swap EDI and other data by email with encryption, signatures and signed receipts. RFC 3886 Tracking Responses An Extensible Message Format for Message Tracking Responses The MIME format a mail server uses to report where a tracked message currently is. RFC 5182 IMAP SEARCHRES IMAP Extension for Referencing the Last SEARCH Result A small IMAP extension that lets a client say "use the messages my last search found" with a single dollar sign. RFC 5255 IMAP i18n Internet Message Access Protocol Internationalization IMAP extensions for choosing the language of server messages and the rules used to search and sort text. RFC 5703 Sieve MIME Sieve Email Filtering: MIME Part Tests, Iteration, Extraction, Replacement, and Enclosure Sieve extensions that let mail filters look inside, loop over, replace and wrap the MIME parts of a message. RFC 6851 IMAP MOVE Internet Message Access Protocol (IMAP) - MOVE Extension One IMAP command that moves messages between mailboxes without the copy, flag and expunge dance. RFC 7672 SMTP DANE SMTP Security via Opportunistic DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) How mail servers use DNSSEC-signed TLSA records to find out that TLS is expected, and to check the server they reach. RFC 2557 MHTML MIME Encapsulation of Aggregate Documents, such as HTML (MHTML) How to pack an HTML page and all its pictures into one MIME email, and how links find the right piece. RFC 3030 SMTP Chunking SMTP Service Extensions for Transmission of Large and Binary MIME Messages Two SMTP extensions: send mail in length-prefixed chunks with BDAT, and send raw binary MIME with no text encoding. RFC 3803 Content Duration MIME Header Definition A one-line mail header that states how many seconds a voice or video attachment lasts. RFC 5429 Sieve reject Sieve Email Filtering: Reject and Extended Reject Extensions Lets a Sieve mail filter refuse a message during delivery, so no bounce goes to a forged sender. RFC 7888 IMAP LITERAL+ IMAP4 Non-synchronizing Literals Lets IMAP clients send string data without waiting for the server's go-ahead, saving a network round trip. RFC 8601 Authentication-Results Message Header Field for Indicating Message Authentication Status A mail header that records which authentication checks a message passed or failed, so later software can act on the results. RFC 561 Mail Headers Standardizing Network Mail Headers An interim proposal to give network mail a standard From, Date and Subject header. RFC 1176 IMAP2 Interactive Mail Access Protocol: Version 2 Keep your mail on a server and let your PC or workstation search, read and manage it there. RFC 2505 Anti-Spam SMTP Anti-Spam Recommendations for SMTP MTAs A 1999 checklist of anti-spam controls that every SMTP mail server should offer, starting with closing open relays. RFC 934 Proposed standard for message encapsulation How to wrap one or more mail messages inside another, and how to unwrap them again. RFC 4289 MIME registration Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures How new MIME external body access types and transfer encodings get onto the official IANA lists. RFC 1767 MIME EDI MIME Encapsulation of EDI Objects Three MIME content types that let businesses send EDI interchanges as ordinary Internet email. RFC 2311 S/MIME v2 S/MIME Version 2 Message Specification How S/MIME version 2 wraps MIME messages in signatures and encryption using PKCS #7 objects. RFC 2919 List-Id List-Id: A Structured Field and Namespace for the Identification of Mailing Lists A mail header that gives each mailing list a stable, domain-based identifier. RFC 3885 SMTP Message Tracking SMTP Service Extension for Message Tracking A way for a sender to tag an outgoing email so its fate can be looked up later if no delivery notice ever arrives. RFC 5819 IMAP LIST-STATUS IMAP4 Extension for Returning STATUS Information in Extended LIST Lets an IMAP client list mailboxes and fetch their message counts in one command instead of one STATUS call per mailbox. RFC 6590 Abuse Report Redaction Redaction of Potentially Sensitive Data from Mail Abuse Reports How to hide who complained in an email abuse report while still letting the receiver spot repeat complaints about the same person. RFC 6785 Sieve IMAP events Support for Internet Message Access Protocol (IMAP) Events in Sieve Lets Sieve mail filters run when IMAP messages are added or flagged, not only when mail is delivered. RFC 6857 Post-Delivery Message Downgrading for Internationalized Email Messages How a POP or IMAP server rewrites internationalized email into plain ASCII headers so old clients can still read it. RFC 8474 IMAP OBJECTID IMAP Extension for Object Identifiers Gives IMAP mailboxes and messages permanent IDs, so a client can tell that something merely moved instead of downloading it again. RFC 9394 IMAP PARTIAL IMAP PARTIAL Extension for Paged SEARCH and FETCH How IMAP clients can ask for a slice of a big search or fetch result instead of everything at once. RFC 3802 audio/32KADPCM Toll Quality Voice - 32 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM) MIME Sub-type Registration Registers the MIME type that carries 32 kbit/s ADPCM telephone-quality voice, with a fixed bit order. RFC 5235 Sieve spamtest Sieve Email Filtering: Spamtest and Virustest Extensions Portable Sieve tests that read a spam or virus score instead of a scanner's own header format. RFC 6856 Post Office Protocol Version 3 (POP3) Support for UTF-8 How POP3 learns to carry UTF-8 text in mail, login names, passwords and server messages. RFC 7377 IMAP Multisearch IMAP4 Multimailbox SEARCH Extension One IMAP command that searches many mailboxes at once, without disturbing the one you have open. RFC 1896 text/enriched The text/enriched MIME Content-type A deliberately tiny set of angle-bracket tags for bold, italic and layout in email. RFC 821 SMTP (Original) Simple Mail Transfer Protocol The original specification for email delivery, still in use (updated) over 40 years later RFC 1424 PEM certification Privacy Enhancement for Internet Electronic Mail: Part IV: Key Certification and Related Services How Privacy-Enhanced Mail users asked a certification authority to sign their key, and to store and fetch revocation lists, all by email. RFC 976 UUCP mail format UUCP mail interchange format standard How UUCP sites wrap Internet-style mail so it can hop from machine to machine without being mangled. RFC 1056 PCMAIL PCMAIL: A distributed mail system for personal computers A 1988 design for mail kept on a central repository, with small personal computers that sync a local copy over a simple text protocol. RFC 937 POP2 Post Office Protocol: Version 2 An early, deliberately simple protocol for fetching mail from a mailbox server to a workstation. RFC 1801 MHS Routing in X.500 MHS use of the X.500 Directory to support MHS Routing Using the X.500 Directory as a global routing table so X.400 mail servers can find the next hop toward a recipient. RFC 680 Message Transmission Protocol A 1975 proposal that defines more ARPANET message header fields on top of the RFC 561 format. RFC 2157 X.400/MIME Bodies Mapping between X.400 and RFC-822/MIME Message Bodies Rules for turning the parts of an X.400 message into MIME parts, and back, at a mail gateway. RFC 2480 Gateways and MIME Security Multiparts What mail gateways to non-MIME systems must do so signed and encrypted messages are not silently broken. RFC 2912 Indicating Media Features for MIME Content A MIME header that labels a message part with the media features needed to handle it. RFC 3503 MDN for IMAP Message Disposition Notification (MDN) profile for Internet Message Access Protocol (IMAP) How several mail programs sharing one IMAP mailbox avoid sending the same read receipt twice. RFC 4406 Sender ID Sender ID: Authenticating E-Mail Check email addresses against DNS records to verify the sender's domain approved the SMTP connection. RFC 4865 FUTURERELEASE SMTP Submission Service Extension for Future Message Release How a mail client can ask its submission server to hold a message and release it at a later time. RFC 4959 IMAP SASL-IR IMAP Extension for Simple Authentication and Security Layer (SASL) Initial Client Response Lets an IMAP client send its first SASL authentication data with the AUTHENTICATE command, saving a round trip. RFC 5068 Email Submission Operations Email Submission Operations: Access and Accountability Requirements Operational rules that make the first hop of email, from a user's mail program to a mail server, accountable. RFC 5232 Sieve imap4flags Sieve Email Filtering: Imap4flags Extension Lets Sieve mail filters set, add, remove and test IMAP flags on a message as it is delivered. RFC 5293 Sieve Editheader Sieve Email Filtering: Editheader Extension Two Sieve actions that let a mail filter script add header fields to a message and delete them. RFC 5490 Sieve mailbox extensions The Sieve Mail-Filtering Language -- Extensions for Checking Mailbox Status and Accessing Mailbox Metadata New Sieve tests that check whether a mailbox exists, read mailbox and server annotations, and create missing folders. RFC 6134 Sieve External Lists Sieve Extension: Externally Stored Lists Reference externally managed lists in email filter rules without rewriting the script. RFC 6154 IMAP Special-Use IMAP LIST Extension for Special-Use Mailboxes How an IMAP server can tell your mail client which folder is Drafts, Sent, Trash and so on. RFC 6650 ARF Applicability Creation and Use of Email Feedback Reports: An Applicability Statement for the Abuse Reporting Format (ARF) Practical advice on when, where and how to send machine-readable email abuse and authentication-failure reports. RFC 6652 SPF Failure Reports Sender Policy Framework (SPF) Authentication Failure Reporting Using the Abuse Reporting Format Three new SPF record settings let a domain ask receivers to mail back reports when SPF checks fail. RFC 6657 MIME charset Update Update to MIME regarding "charset" Parameter Handling in Textual Media Types Retires the old rule that text media types without a charset parameter are assumed to be US-ASCII. RFC 6858 Simplified POP and IMAP Downgrading for Internationalized Email A deliberately simple way for IMAP and POP servers to show internationalized mail to old clients, with some information lost. RFC 8580 Sieve FCC Sieve Extension: File Carbon Copy (FCC) How a Sieve mail filter can keep a copy of the automatic replies and notifications it sends for you. RFC 2789 Mail Monitoring MIB Mail Monitoring MIB SNMP objects that let a management system watch message flow, queues and errors inside a mail server. RFC 2822 Internet Message Format Internet Message Format The rules for what an email message looks like: header lines, a blank line, then the body. RFC 3302 image/tiff MIME type Tag Image File Format (TIFF) - image/tiff MIME Sub-type Registration The official registration of image/tiff, the MIME label for TIFF pictures. RFC 3676 text/plain format The Text/Plain Format and DelSp Parameters How a trailing space lets plain-text email reflow to any screen while still reading as ordinary text. RFC 3950 TIFF-FX MIME Type Tag Image File Format Fax eXtended (TIFF-FX) - image/tiff-fx MIME Sub-type Registration Registers image/tiff-fx, the MIME type for Internet fax image files. RFC 5034 POP3 SASL The Post Office Protocol (POP3) Simple Authentication and Security Layer (SASL) Authentication Mechanism How a POP3 client logs in using any SASL mechanism, with the AUTH command and the SASL capability. RFC 1524 Mailcap A User Agent Configuration Mechanism For Multimedia Mail Format Information A shared configuration file that tells every mail reader which program handles which kind of mail content. RFC 2033 LMTP Local Mail Transfer Protocol A variant of SMTP for handing mail to a delivery system that keeps no queue, with one reply per recipient. RFC 2785 Methods for Avoiding the "Small-Subgroup" Attacks on the Diffie-Hellman Key Agreement Method for S/MIME When and how S/MIME implementations should defend Diffie-Hellman keys against attackers who send deliberately weak public keys. RFC 4686 DKIM threat analysis Analysis of Threats Motivating DomainKeys Identified Mail (DKIM) The security problems that signature-based email authentication was designed to prevent. RFC 1846 SMTP 521 SMTP 521 Reply Code A new SMTP reply code that lets a host say plainly that it does not take mail. RFC 1521 MIME MIME (Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies How Internet email learned to carry attachments, images and non-ASCII text without breaking the old message format. RFC 2048 Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures The rules for adding new media types, access types and transfer encodings to MIME through IANA. RFC 759 MPM Internet Message Protocol A comprehensive protocol for transmitting messages and multimedia between networked computers. RFC 2193 IMAP4 Referrals IMAP4 Mailbox Referrals How an IMAP server can point a client to another server that holds a mailbox. RFC 3362 image/t38 MIME type Real-time Facsimile (T.38) - image/t38 MIME Sub-type Registration Official MIME type for real-time faxing over the internet. RFC 3854 S/MIME for X.400 Securing X.400 Content with Secure/Multipurpose Internet Mail Extensions (S/MIME) How to sign and encrypt the contents of an X.400 message using the same S/MIME and CMS machinery as Internet mail. RFC 3865 SMTP No Soliciting A No Soliciting Simple Mail Transfer Protocol (SMTP) Service Extension An SMTP extension that works like a No Soliciting sign: a mail server says which kinds of solicitation it does not want. RFC 4262 S/MIME capabilities cert X.509 Certificate Extension for Secure/Multipurpose Internet Mail Extensions (S/MIME) Capabilities Advertise cryptographic capabilities in a certificate extension. RFC 5064 Archived-At header The Archived-At Message Header Field An email header that points straight to the archived copy of that one message. RFC 5173 Sieve body Sieve Email Filtering: Body Extension How a Sieve mail filter can look inside the body of a message, not just its headers. RFC 5259 IMAP CONVERT Internet Message Access Protocol - CONVERT Extension An IMAP extension that lets a client ask the server to convert attachments and headers before download. RFC 5423 Message Store Events Internet Message Store Events A common list of the things a mail store can report, such as new mail, deleted messages and quota changes. RFC 5436 Sieve mailto Sieve Notification Mechanism: mailto How a Sieve mail filter can ping you by sending a brand-new email, without starting a mail loop. RFC 6651 DKIM Failure Reports Extensions to DomainKeys Identified Mail (DKIM) for Failure Reporting How a domain can ask receivers to report back when its DKIM signatures fail to verify. RFC 6710 SMTP MT-PRIORITY Simple Mail Transfer Protocol Extension for Message Transfer Priorities A way for a mail message to carry a priority from -9 to 9 so busy servers can move urgent mail first. RFC 7372 Email Authentication Status Codes New SMTP status codes that tell a sender its message was refused because it failed email authentication checks. RFC 7504 SMTP 521 and 556 Reply Codes Two SMTP reply codes that let a host say plainly: this machine does not accept mail at all. RFC 8461 MTA-STS SMTP MTA Strict Transport Security (MTA-STS) How a mail domain can tell senders: deliver to us only over properly authenticated TLS. RFC 8579 Sieve Special-Use Sieve Email Filtering: Delivering to Special-Use Mailboxes Lets a Sieve mail filter file messages into the Junk, Sent or Archive folder by its job rather than its name. RFC 8616 Email Auth for IDN Email Authentication for Internationalized Mail Settles which form of an internationalized domain name SPF, DKIM and DMARC must use, so mail with non-ASCII addresses can be authenticated. RFC 9007 JMAP MDN Handling Message Disposition Notification with the JSON Meta Application Protocol (JMAP) How a JMAP mail client sends and reads read receipts through two small methods, MDN/send and MDN/parse. RFC 9404 JMAP Blob JSON Meta Application Protocol (JMAP) Blob Management Extension JMAP extension for creating and reading blobs inside ordinary method calls, plus a reverse lookup of where blobs are used. RFC 9670 JMAP Sharing JSON Meta Application Protocol (JMAP) Sharing A common JMAP model for principals, share notifications and per-object sharing rights. RFC 1465 Routing Coordination for X.400 MHS Services Within a Multi Protocol / Multi Network Environment Table Format V3 for Static Routing A table-based format for coordinating X.400 mail routing across multiple networks and stacks. RFC 1641 Unicode in MIME Using Unicode with MIME How to label and send 16-bit Unicode text inside MIME mail, and how to name Unicode character sets. RFC 1733 IMAP4 mail models Distributed Electronic Mail Models in IMAP4 Three ways of doing client/server email, offline, online and disconnected, and how IMAP4 can serve all of them. RFC 4021 Registration of Mail and MIME Header Fields The first official IANA list of permanent mail and MIME header fields, from Date and Subject to Content-Type. RFC 4134 Examples of S/MIME Messages Real-world examples of cryptographic email messages for testing and interoperability RFC 4143 IFax ENUM service Facsimile Using Internet Mail (IFAX) Service of ENUM Registers the E2U+ifax ENUM service so a telephone number can resolve to an email address for fax. RFC 5383 Lemonade Deployment Deployment Considerations for Lemonade-Compliant Mobile Email What networks, firewalls and NATs must allow so that mobile email over IMAP and Message Submission works. RFC 6377 DomainKeys Identified Mail (DKIM) and Mailing Lists Best practices for keeping DKIM useful when mailing lists rewrite the messages that pass through them. RFC 6449 Complaint feedback loops Complaint Feedback Loop Operational Recommendations How mailbox providers report spam complaints back to senders. RFC 7960 DMARC & Indirect Mail Interoperability Issues between Domain-based Message Authentication, Reporting, and Conformance (DMARC) and Indirect Email Flows Why strict DMARC policies break mailing lists, forwarders and other mail that does not travel straight from author to reader. RFC 1869 SMTP Extensions SMTP Service Extensions How a mail server announces its optional features, starting with the EHLO greeting. RFC 2821 SMTP Simple Mail Transfer Protocol The self-contained rulebook for moving Internet email between servers: commands, replies, relaying and retries. RFC 2061 IMAP4 and IMAP2bis IMAP4 Compatibility with IMAP2bis How to make an IMAP4 program get along with the older, widely used IMAP2bis servers and clients. RFC 2152 UTF-7 UTF-7 A Mail-Safe Transformation Format of Unicode A way to write any Unicode text using only 7-bit ASCII, so it survives old mail systems. RFC 1049 Content-Type header Content-type header field for Internet messages An early proposal for an email header that says how a message body is structured, such as PostScript or TROFF. RFC 4405 SMTP SUBMITTER SMTP Service Extension for Indicating the Responsible Submitter of an E-Mail Message An SMTP extension to identify the party responsible for submitting a message RFC 4407 Purported Resp. Address Purported Responsible Address in E-Mail Messages An algorithm for finding who appears to have sent an email by examining its headers RFC 1327 Mapping between X.400(1988) / ISO 10021 and RFC 822 A translation guide that lets X.400 mail systems and RFC 822 Internet mail exchange messages through a gateway. RFC 3798 MDN Message Disposition Notification The standard format for read receipts: how a sender asks for one and how the recipient's mail program reports back. RFC 1864 Content-MD5 The Content-MD5 Header Field An optional MIME header that carries an MD5 digest so a receiver can check a message body arrived intact. RFC 5233 Sieve subaddress Sieve Email Filtering: Subaddress Extension Lets Sieve mail filters look at the user and detail parts of addresses like ken+sieve@example.org. RFC 5257 IMAP ANNOTATE Internet Message Access Protocol - ANNOTATE Extension How an IMAP server can store comments, flags and other notes on messages and on individual message parts. RFC 6318 Suite B in Secure/Multipurpose Internet Mail Extensions (S/MIME) Which NSA Suite B algorithms an S/MIME email system must use, and how to plug them into signing and encryption. RFC 9208 IMAP QUOTA IMAP QUOTA Extension How an IMAP client asks a mail server how much space it has used, and what the limit is. RFC 9755 IMAP UTF-8 IMAP Support for UTF-8 How IMAP servers and clients negotiate UTF-8 for mailbox names, quoted strings and internationalized message headers. RFC 1732 IMAP4 compatibility IMAP4 Compatibility with IMAP2 and IMAP2bis Hints for making an IMAP4 client or server get along with older IMAP2 and IMAP2bis software. RFC 2062 IMAP Obsolete Syntax Internet Message Access Protocol - Obsolete Syntax Commands and responses no longer used in modern IMAP implementations RFC 2076 Common Message Headers Common Internet Message Headers A one-stop reference table of the header fields found at the top of Internet mail and Usenet messages. RFC 2180 IMAP4 Multi-Accessed Mailbox Practice What IMAP4 servers may do, and what clients must expect, when several clients use one mailbox at once. RFC 3114 Implementing Company Classification Policy with the S/MIME Security Label How to mark secure email with company classification levels RFC 3348 IMAP4 CHILDREN The Internet Message Action Protocol (IMAP4) Child Mailbox Extension Two LIST attributes that tell an IMAP client whether a mailbox has child mailboxes, without extra LIST commands. RFC 4549 Disconnected IMAP4 sync Synchronization Operations for Disconnected IMAP4 Clients How a mail client that works offline should use IMAP commands to bring its local copy back in step with the server. RFC 5585 DKIM overview DomainKeys Identified Mail (DKIM) Service Overview A guided tour of DKIM: how a domain can sign an email so receivers can verify who took responsibility for it. RFC 524 Mail Protocol Proposed Mail Protocol John White's 1973 proposal for a mail protocol that lives inside FTP and goes far beyond the MAIL and MLFL commands. RFC 630 FTP FTP error code usage for more reliable mail service How TENEX sites will use the existing FTP error codes so mail senders can tell permanent failures from temporary ones. RFC 1137 822 Restricted Mapping Mapping between full RFC 822 and RFC 822 with restricted encoding A reversible encoding that lets awkward RFC 822 addresses survive mail systems with a restricted character set. RFC 1328 X.400 Downgrading X.400 1988 to 1984 downgrading How gateways should downgrade X.400 1988 messages and addresses for 1984 systems. RFC 1740 MacMIME MIME Encapsulation of Macintosh Files - MacMIME How to mail a two-part Macintosh file through MIME without losing either part. RFC 1848 MOSS MIME Object Security Services Signing and encrypting MIME email with plain public key pairs, no certificates required. RFC 1985 SMTP ETRN SMTP Service Extension for Remote Message Queue Starting ETRN lets a mail client ask a server to start sending the mail it is holding for that client. RFC 2017 URL External-Body Type Definition of the URL MIME External-Body Access-Type How a MIME mail message can point at its content with a URL instead of carrying the data. RFC 2158 X.400 Image Body Parts Defines how JPEG and GIF images are carried through X.400 mail and mapped to their MIME types. RFC 2160 Carrying PostScript in X.400 and MIME Two ways to carry PostScript through X.400 mail, and how each maps to MIME's application/postscript. RFC 2384 POP URL POP URL Scheme A way to write the address of a POP mailbox as a link, with the server, port and login method in one string. RFC 2913 MIME type feature tag MIME Content Types in Media Feature Expressions A media feature tag called type that lets a capability expression say which MIME content types it covers. RFC 2971 IMAP ID IMAP4 ID extension An IMAP command that lets clients and servers tell each other what software they are, for bug reports and statistics. RFC 3003 audio/mpeg The audio/mpeg Media Type Registers the MIME type for MPEG audio files, including MP3 RFC 3206 POP SYS and AUTH The SYS and AUTH POP Response Codes Two POP3 error codes and a capability that tell a mail client whether a failed login is the user's fault or the server's. RFC 3691 IMAP UNSELECT Internet Message Access Protocol (IMAP) UNSELECT command Close a mailbox without deleting messages marked for removal. RFC 3804 VPIM Addressing Voice Profile for Internet Mail (VPIM) Addressing How to write email addresses that point at voice mailboxes, outdialing devices and AMIS voice networks. RFC 3848 ESMTP and LMTP Types ESMTP and LMTP Transmission Types Registration Seven new keywords that let a Received header record whether mail travelled over ESMTP or LMTP, with encryption or login. RFC 3855 S/MIME in X.400 Transporting Secure/Multipurpose Internet Mail Extensions (S/MIME) Objects in X.400 How to carry S/MIME-protected objects inside native X.400 messages, and how to label them. RFC 3894 Sieve Copy Sieve Extension: Copying Without Side Effects A Sieve ':copy' option that files or forwards an extra copy of a message without cancelling normal delivery. RFC 3938 Video-Message Message-Context One new Message-Context value, video-message, so mail programs can tell a video email from other kinds. RFC 3939 Calling Line Identification for Voice Mail Messages Two mail headers that keep a caller's number and name with a stored voice mail message. RFC 4141 SMTP and MIME Extensions for Content Conversion How mail servers along the way can convert a message into a form the recipient can handle, with the sender's permission. RFC 4142 FFPIM Full-mode Fax Profile for Internet Mail (FFPIM) Closing the gap between email-based fax and classic fax with content negotiation and richer TIFF. RFC 4978 IMAP COMPRESS The IMAP COMPRESS Extension How an IMAP client and server agree to squeeze everything they send each other with DEFLATE. RFC 5183 Sieve environment Sieve Email Filtering: Environment Extension A Sieve extension that lets an email filter script ask about the system it is running on. RFC 5437 Sieve XMPP Sieve Notification Mechanism: Extensible Messaging and Presence Protocol (XMPP) How a Sieve mail filter can ping you with an XMPP (Jabber) instant message when new mail arrives. RFC 5530 IMAP response codes IMAP Response Codes Seventeen named reasons an IMAP server can give, in a form programs can read, when it says no. RFC 5593 IMAP URL access IDs Internet Message Access Protocol (IMAP) - URL Access Identifier Extension New access identifiers for URLAUTH IMAP URLs, so services such as streaming can fetch mail on a user's behalf without abusing submit+. RFC 5957 IMAP SORT display Display-Based Address Sorting for the IMAP4 SORT Extension IMAP sort criteria that order messages by the name people see in From and To, not the bare address. RFC 6131 Sieve Vacation Seconds Sieve Vacation Extension: "Seconds" Parameter Lets a Sieve auto-reply wait seconds, not days, before replying to the same sender again. RFC 6132 Sieve Presence Sieve Notification Using Presence Information Lets a Sieve mail filter check whether you are busy, away or offline before it decides how to notify you. RFC 6203 IMAP fuzzy search IMAP4 Extension for Fuzzy Search An IMAP extension that lets servers match mail loosely and score each hit by relevancy. RFC 6609 Sieve Include Sieve Email Filtering: Include Extension Lets one Sieve email filter script pull in another, with shared variables and personal or site-wide libraries. RFC 6692 ARF Source Port Source Ports in Abuse Reporting Format (ARF) Reports A new ARF header field that names the source port, so an abuse report can pinpoint who sent the mail. RFC 6854 Group From: Update to Internet Message Format to Allow Group Syntax in the "From:" and "Sender:" Header Fields Email's From: and Sender: headers may now use group syntax, mainly so a message can say it has no address to reply to. RFC 7505 Null MX A "Null MX" No Service Resource Record for Domains That Accept No Mail A single MX record that tells the world a domain accepts no email, so senders give up at once. RFC 7889 IMAP APPENDLIMIT The IMAP APPENDLIMIT Extension An IMAP extension that tells clients the largest message a server will accept before they upload it. RFC 8058 Signaling One-Click Functionality for List Email Headers A signed email header that tells mail systems they can unsubscribe a user with one automatic HTTPS POST. RFC 8301 DKIM Crypto Update Cryptographic Algorithm and Key Usage Update to DomainKeys Identified Mail (DKIM) DKIM signers must use rsa-sha256 and keys of at least 1024 bits; rsa-sha1 is retired. RFC 8457 IMAP \Important IMAP "$Important" Keyword and "\Important" Special-Use Attribute A message keyword and a folder attribute that let IMAP servers say 'this mail is probably important to you'. RFC 8460 SMTP TLS Reporting SMTP TLS Reporting How mail senders tell recipient domains when encrypted delivery worked, failed, or was attacked. RFC 8463 DKIM Ed25519 A New Cryptographic Signature Method for DomainKeys Identified Mail (DKIM) Adds Ed25519-SHA256 to DKIM: a signature scheme with much shorter keys than RSA, which every verifier must support. RFC 8689 SMTP REQUIRETLS SMTP Require TLS Option Lets an email sender demand encrypted, authenticated delivery, or explicitly waive it, one message at a time. RFC 9042 Sieve MAILBOXID Sieve Email Filtering: Delivery by MAILBOXID Lets Sieve mail filters file messages by a mailbox's permanent ID, so renaming a folder does not break the rules. RFC 9425 JMAP Quotas JSON Meta Application Protocol (JMAP) for Quotas A JMAP data type that lets a client see how much of its allowance it has used, and where the limits are. RFC 10022 IMAP UIDBATCHES IMAP UIDBATCHES Extension An IMAP command that hands a client ready-made UID ranges for working through a big mailbox in equal batches. RFC 3555 MIME Type Registration of RTP Payload Formats How to give each RTP payload format a MIME name, and the first batch of names for audio and video. RFC 7489 DMARC Domain-based Message Authentication, Reporting, and Conformance (DMARC) How a domain owner publishes in DNS what receivers should do with mail that fails authentication, and how receivers report back. RFC 4871 DKIM DomainKeys Identified Mail (DKIM) Signatures How a domain signs outgoing email and publishes the key in DNS so receivers can check the message. RFC 974 MX routing Mail routing and the domain system How a mail server uses DNS MX records to decide where to deliver a message. RFC 5451 Auth-Results Header Message Header Field for Indicating Message Authentication Status A mail header that records which authentication checks a message passed or failed, for filters and mail programs downstream. RFC 987 X.400 to RFC 822 Mapping between X.400 and RFC 822 The first rulebook for gateways that translate email between X.400 systems and RFC 822 Internet mail. RFC 1203 IMAP3 Interactive Mail Access Protocol: Version 3 A counter-proposal to extend IMAP2 so workstations can read mail that stays on a server, with version and feature negotiation built in. RFC 7001 Message Header Field for Indicating Message Authentication Status A standard email header that records which sender checks a message passed, so later software can sort and filter on them. RFC 2060 IMAP4rev1 Internet Message Access Protocol - Version 4rev1 Keep your email on a server and work with it from anywhere, as if the mailboxes were local. RFC 5751 S/MIME 3.2 Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message Specification How to sign, encrypt and compress MIME messages so email and other MIME traffic can be secured end to end. RFC 3851 S/MIME 3.1 Messages Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message Specification How to sign, encrypt and compress MIME data with S/MIME version 3.1, built on the Cryptographic Message Syntax. RFC 1844 MIME UA Checklist Multimedia E-mail (MIME) User Agent Checklist A questionnaire for judging how well an email program handles MIME, plus a robot that mails you test messages. RFC 3656 MUPDATE The Mailbox Update (MUPDATE) Distributed Mailbox Database Protocol A small text protocol that lets many mail servers share one authoritative list of which mailbox lives where. RFC 6783 Lists & non-ASCII Mailing Lists and Non-ASCII Addresses What mailing lists have to think about when some subscribers use non-ASCII UTF-8 email addresses. RFC 1894 DSN Message Format An Extensible Message Format for Delivery Status Notifications A machine-readable MIME format for the reports mail systems send back about whether a message was delivered. RFC 1522 MIME headers MIME (Multipurpose Internet Mail Extensions) Part Two: Message Header Extensions for Non-ASCII Text How to put non-ASCII text, such as accented names, into email headers using encoded-words. RFC 1341 MIME MIME (Multipurpose Internet Mail Extensions): Mechanisms for Specifying and Describing the Format of Internet Message Bodies How email learned to carry pictures, sounds, attachments and non-ASCII text without breaking old mail systems. RFC 2633 S/MIME v3 S/MIME Version 3 Message Specification How to add cryptographic signatures and encryption to MIME email messages. RFC 4408 SPF v1 Sender Policy Framework (SPF) for Authorizing Use of Domains in E-Mail, Version 1 How a domain publishes, in DNS, which mail servers may send email using its name, and how receivers check it. RFC 453 Meeting announcement to discuss a network mail system SRI-ARC calls a February 1973 meeting to decide how mail should work across the early ARPANET. RFC 475 FTP FTP and Network Mail System A 1973 discussion paper on putting network mail inside FTP, with six mail functions and new commands. RFC 539 Thoughts on the mail protocol proposed in RFC 524 Crocker and Postel review the mail protocol proposed in RFC 524, with minor and major objections. RFC 555 Responses to critiques of the proposed mail protocol James White answers the questions and complaints that his RFC 524 mail protocol proposal drew. RFC 767 Structured format for transmission of multi-media documents A format for sending documents that mix text, images, fax, and voice through computer mail. RFC 1090 SMTP on X.25 SMTP on X.25 Running SMTP mail transfer directly over X.25 virtual circuits instead of TCP. RFC 2088 IMAP4 Literal+ IMAP4 non-synchronizing literals Let an IMAP client send a string without pausing for the server's go-ahead. RFC 4409 Mail Submission Port 587 Message Submission for Mail Why mail clients should hand outgoing mail to a separate submission server, normally on port 587. RFC 6522 Multipart/Report The Multipart/Report Media Type for the Reporting of Mail System Administrative Messages The MIME container that wraps a mail system report: a human note, a machine-readable account and, optionally, the original message. RFC 1211 Problems with the maintenance of large mailing lists What running the IETF mailing lists taught ISI about bounced mail, sublists and misdirected requests. RFC 1437 The Extension of MIME Content-Types to a New Medium A humorous MIME type for transporting sentient beings via email. RFC 1506 A Tutorial on Gatewaying between X.400 and Internet Mail How to translate mail between X.400 and Internet standards using RFC 1327 mapping rules RFC 1556 Handling of Bi-directional Texts in MIME How to handle text that runs right-to-left (or switches direction) in email. RFC 1615 Migrating from X.400(84) to X.400(88) Planning the upgrade from X.400(84) to the newer X.400(88) email standard. RFC 1649 Operational Requirements for X.400 Management Domains in the GO-MHS Community Rules for connecting global X.400 email services into one community. RFC 1685 Writing X.400 O/R Names A uniform way for people to write down the many-part addresses used by X.400 email. RFC 2162 MaXIM-11 MaXIM-11 - Mapping between X.400 / Internet mail and Mail-11 mail Rules for translating addresses and message elements between DECnet Mail-11, X.400 and Internet mail. RFC 3098 How to Advertise Responsibly Using E-Mail and Newsgroups or - how NOT to $$$$$ MAKE ENEMIES FAST! $$$$$ Guidelines for ethical email and newsgroup marketing RFC 3249 Implementers Guide for Facsimile Using Internet Mail Practical fixes and cautions for anyone building software that sends faxes over Internet mail. RFC 3773 High-Level Requirements for Internet Voice Mail What voice mail systems must do to work together over the Internet. RFC 4024 VPIM Client Behaviour Voice Messaging Client Behaviour How email clients should display and handle voice and fax messages. RFC 4146 Simple New Mail Notification A simple technique that tells a client when new mail arrives RFC 4155 application/mbox The application/mbox Media Type The MIME type and standard format for mailbox files containing email messages. RFC 4496 OPES SMTP use cases Open Pluggable Edge Services (OPES) SMTP Use Cases Practical applications for processing email at network gateways using the OPES framework. RFC 4952 Internationalized Email Overview and Framework for Internationalized Email The roadmap for letting email addresses and headers use people's own names and scripts, in UTF-8. RFC 5016 DKIM SSP Requirements Requirements for a DomainKeys Identified Mail (DKIM) Signing Practices Protocol Requirements for publishing DKIM signing practices to help detect spoofed mail. RFC 5442 LEMONADE Architecture LEMONADE Architecture - Supporting Open Mobile Alliance (OMA) Mobile Email (MEM) Using Internet Mail How ordinary Internet mail protocols map onto the Open Mobile Alliance's architecture for email on mobile devices. RFC 5551 Lemonade notifications Lemonade Notifications Architecture How email systems can tell phones and other constrained clients that something interesting happened, without constant polling. RFC 5863 DKIM Operations DomainKeys Identified Mail (DKIM) Development, Deployment, and Operations Practical advice for building, deploying and running DKIM email signing, from key handling to mailing lists. RFC 6133 Sieve Auto-Responder Sieve Email Filtering: Use of Presence Information with Auto-Responder Functionality Using email filtering rules to send smart automatic replies based on presence and address book. RFC 6686 SPF and Sender ID Resolution of the Sender Policy Framework (SPF) and Sender ID Experiments A report card on SPF and Sender ID: after six years of surveys, SPF won and the experiments were declared concluded. RFC 8755 CNSA suite in S/MIME Using Commercial National Security Algorithm Suite Algorithms in Secure/Multipurpose Internet Mail Extensions Using NSA-approved cryptographic algorithms in secure email. RFC 1026 X.400 to RFC 822 Addendum to RFC 987: (Mapping between X.400 and RFC-822) Corrections and additions to the X.400 to RFC 822 mail mapping defined in RFC 987. RFC 2440 OpenPGP OpenPGP Message Format The packet formats that let different programs encrypt, sign and exchange OpenPGP data. RFC 733 Standard for the format of ARPA network text messages The standard for how to format and parse email headers and message text on the ARPANET. RFC 1651 SMTP Extensions SMTP Service Extensions The EHLO handshake that lets an SMTP server announce which optional features it supports. RFC 2421 VPIM v2 Voice Profile for Internet Mail - version 2 Standard format for sending voice mail messages over Internet email. RFC 3850 S/MIME 3.1 Certificates Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Certificate Handling How S/MIME email agents validate and use X.509 certificates. RFC 2476 Mail Submission Message Submission Why email clients should hand new messages to a dedicated submission server on port 587, and what that server should do. RFC 1425 ESMTP SMTP Service Extensions A framework for adding new features to SMTP without breaking old implementations RFC 1893 Enhanced Status Codes Enhanced Mail System Status Codes Machine-readable codes that say exactly what went wrong with email delivery. RFC 2192 IMAP URL IMAP URL Scheme A standard way to write a link to an IMAP server, a mailbox, a search result, a message or one part of a message. RFC 2368 mailto URL The mailto URL scheme Web links that open your email program with a message ready to send. RFC 2426 vCard 3.0 vCard MIME Directory Profile A standard format for exchanging digital business cards and contact information RFC 3028 Sieve Sieve: A Mail Filtering Language A safe, scriptable language for filtering email at delivery time. RFC 4551 IMAP CONDSTORE IMAP Extension for Conditional STORE Operation or Quick Flag Changes Resynchronization Conditional flag updates and quick resynchronization for shared IMAP mailboxes. RFC 278 Revision of the Mail Box Protocol A 1971 revision of the Mail Box Protocol, which sends plain text mail to a line printer using FTP. RFC 402 ARPA Network Mailing Lists Three October 1972 distribution lists the Network Information Center used to mail RFCs and other network documents. RFC 841 Specification for message format for Computer Based Message Systems A US federal standard for what goes inside an electronic message, republished as an RFC for ARPA researchers. RFC 2161 A MIME Body Part for ODA Carries office documents in email using a standard format RFC 2298 MDN An Extensible Message Format for Message Disposition Notifications A standard format for email read receipts and delivery confirmations. RFC 8617 ARC The Authenticated Received Chain (ARC) Protocol A chain of signed header fields that lets each mail handler record what authentication checks the message passed. RFC 9586 IMAP UIDONLY IMAP Extension for Using and Returning Unique Identifiers (UIDs) Only An IMAP extension that drops message sequence numbers entirely, so clients and servers talk only in permanent UIDs. RFC 9738 IMAP MESSAGELIMIT IMAP MESSAGELIMIT Extension A way for an IMAP server to announce how many messages one command may touch, so clients can work in batches. RFC 1590 Media Type Registration Media Type Registration Procedure How new MIME media types get registered with IANA, and why the original rules were loosened. RFC 1138 X.400 and RFC 822 Mapping between X.400(1988) / ISO 10021 and RFC 822 A rulebook for gateways that translate mail between X.400 (1988) systems and Internet RFC 822 mail. RFC 5750 S/MIME 3.2 Certs Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Certificate Handling How mail programs check and use digital ID certificates for secure email. RFC 6855 IMAP Support for UTF-8 International characters in email servers and addresses RFC 1730 IMAP4 Internet Message Access Protocol - Version 4 Protocol for accessing and managing email messages on a server. RFC 1734 POP3 AUTH POP3 AUTHentication command A secure way for mail programs to log into servers using stronger authentication methods. RFC 1891 SMTP DSN Extension SMTP Service Extension for Delivery Status Notifications Let email senders request delivery status notifications under chosen conditions. RFC 2425 MIME Directory A MIME Content-Type for Directory Information A standard text format for structuring directory information in email messages. RFC 1113 PEM Part I Privacy enhancement for Internet electronic mail: Part I - message encipherment and authentication procedures How to encrypt and authenticate Internet electronic mail so recipients know the message is real and unopened. RFC 1652 8BITMIME SMTP Service Extension for 8bit-MIMEtransport How two mail servers agree to pass message bodies that use 8-bit characters, not just 7-bit ASCII. RFC 2305 Simple Mode Fax A Simple Mode of Facsimile Using Internet Mail Sending fax documents over Internet mail using TIFF format. RFC 7601 Authentication-Results Message Header Field for Indicating Message Authentication Status A header that tells mail software which authentication checks a message passed, such as SPF and DKIM. RFC 1342 MIME Header Encoding Representation of Non-ASCII Text in Internet Message Headers Encoding non-ASCII characters in email headers using a printable ASCII wrapper. RFC 2304 Minimal FAX address format in Internet Mail A standard format for putting fax numbers in email addresses. RFC 2554 SMTP AUTH SMTP Service Extension for Authentication Letting mail clients prove their identity to the mail server before sending mail. RFC 1225 POP3 Post Office Protocol: Version 3 How lightweight workstations retrieve mail from a server without running their own mail system. RFC 2112 Multipart/Related The MIME Multipart/Related Content-type A standard way to send related documents together, like HTML with its images. RFC 2197 SMTP Pipelining SMTP Service Extension for Command Pipelining A faster way to send mail by bundling commands together RFC 5336 SMTPUTF8 SMTP Extension for Internationalized Email Addresses Sending email with addresses and text written in any alphabet. RFC 5335 Internationalized Email Headers UTF-8 characters in email headers instead of ASCII encoding RFC 458 FTP Mail retrieval via FTP Reading mail through the file transfer protocol without logging in. RFC 510 Request for network mailbox addresses Asking for email addresses so the NIC can send journal articles over the network RFC 753 Internet Message Protocol Internet Message Protocol Protocol for routing and delivering messages across interconnected networks RFC 771 Mail transition plan A plan for keeping mail working while switching from ARPANET to Internet protocols. RFC 784 Mail Transfer Protocol: ISI TOPS20 implementation How ISI built a mail system for TOPS-20 using the new Internet protocols. RFC 785 Mail Transfer Protocol: ISI TOPS20 file definitions The file formats for ISI TOPS-20's MTP mail system. RFC 1047 Duplicate messages and SMTP Why SMTP can deliver the same message twice and how to prevent it. RFC 1496 Rules for downgrading messages from X.400/88 to X.400/84 when MIME content-types are present in the messages Converting modern MIME email to an older email system format. RFC 1648 Postmaster Convention for X.400 Operations A convention for supporting the postmaster address in X.400 mail domains mapped to RFC 822. RFC 2159 A MIME Body Part for FAX How to carry a Group 3 fax inside a MIME email message, and map it to and from X.400. RFC 2221 IMAP4 Login Referrals IMAP4 Login Referrals How an IMAP4 server can send a client to the server that actually holds the user's mailbox. RFC 2312 S/MIME v2 Certificates S/MIME Version 2 Certificate Handling How S/MIME version 2 mail programs create, check and manage X.509 certificates. RFC 2645 ODMR ON-DEMAND MAIL RELAY (ODMR) SMTP with Dynamic IP Addresses How a mail server with a changing IP address can call its provider and ask for the mail waiting for it. RFC 4095 Solicitation Keywords Attaching Meaning to Solicitation Class Keywords How to turn a reversed-domain spam label into a web page that explains what the label means. RFC 4356 MMS to Email Mapping Mapping Between the Multimedia Messaging Service (MMS) and Internet Mail How a phone's multimedia messages are translated to and from ordinary Internet email, header by header. RFC 5032 IMAP WITHIN WITHIN Search Extension to the IMAP Protocol Two IMAP search keys, OLDER and YOUNGER, that match mail by how many seconds ago it arrived. RFC 5260 Sieve Date and Index Sieve Email Filtering: Date and Index Extensions Two Sieve extensions: test dates and times in mail filters, and pick which copy of a repeated header to test. RFC 5463 Sieve ihave Sieve Email Filtering: Ihave Extension Lets a Sieve mail filter script use optional extensions only when they are available, and fail cleanly when they are not. RFC 5466 IMAP Filters IMAP4 Extension for Named Searches (Filters) Save a favorite IMAP search on the server under a name, then reuse it by name in later searches. RFC 5524 URLFETCH binary Extended URLFETCH for Binary and Converted Parts Lets IMAP URLFETCH return decoded content and type metadata for a message part, not just the raw encoded bytes. RFC 5784 Sieve XML Sieve Email Filtering: Sieves and Display Directives in XML A way to write Sieve mail filters as XML, plus extra elements that let graphical editors group and label rules. RFC 6008 Auth-Results header.b Authentication-Results Registration for Differentiating among Cryptographic Results A small registry addition that lets a mail checker say which DKIM signature each result belongs to. RFC 6009 Sieve Email Filtering: Delivery Status Notifications and Deliver-By Extensions Lets a Sieve mail filter read and set delivery-notification and delivery-deadline settings on the message envelope. RFC 6212 VBR results Authentication-Results Registration for Vouch by Reference Results A small registry update that lets a mail system record the outcome of a Vouch By Reference check in a message header. RFC 6430 ARF not-spam Email Feedback Report Type Value: not-spam A new feedback report type that lets a mail user say a message was wrongly marked as spam. RFC 6468 Sieve SIP notification Sieve Notification Mechanism: SIP MESSAGE How a Sieve mail filter can tell you about new mail by sending a SIP instant message. RFC 6558 Sieve CONVERT Sieve Extension for Converting Messages before Delivery A Sieve action and test that converts message attachments, such as shrinking images, before delivery. RFC 6647 Email Greylisting Email Greylisting: An Applicability Statement for SMTP How and why mail servers temporarily turn away unknown senders, and what it costs legitimate mail. RFC 6729 Email handling states Indicating Email Handling States in Trace Fields A small addition to the Received header that says when an email was put aside, and why. RFC 7293 RRVS The Require-Recipient-Valid-Since Header Field and SMTP Service Extension A way for a sender to say "I knew who owned this mailbox at this time", so mail is not delivered to a later owner. RFC 7352 Sieve duplicate Sieve Email Filtering: Detecting Duplicate Deliveries A Sieve test that lets an email filter notice it has already seen a message and handle the copy. RFC 8437 IMAP UNAUTHENTICATE IMAP UNAUTHENTICATE Extension for Connection Reuse A new IMAP command that lets an administrative client switch users without hanging up and reconnecting. RFC 8438 IMAP STATUS=SIZE IMAP Extension for STATUS=SIZE Ask an IMAP server for the total size of a mailbox with one STATUS command. RFC 8440 IMAP LIST-MYRIGHTS IMAP4 Extension for Returning MYRIGHTS Information in Extended LIST One IMAP LIST command can now return each mailbox together with the rights you hold on it. RFC 8508 IMAP REPLACE IMAP REPLACE Extension An IMAP command that swaps one stored message for a new one in a single step, built for saving drafts as you type. RFC 8514 IMAP SAVEDATE Internet Message Access Protocol (IMAP) - SAVEDATE Extension An IMAP extension that adds a save date: the moment a message landed in its current mailbox, which cannot be faked or copied. RFC 8887 JMAP over WebSocket A JSON Meta Application Protocol (JMAP) Subprotocol for WebSocket How JMAP clients and servers can keep one authenticated WebSocket open instead of authenticating every HTTP request. RFC 8970 IMAP PREVIEW IMAP4 Extension: Message Preview Generation Lets an IMAP mail client ask the server for a short, ready-made text preview of each message. RFC 9219 S/MIME Signature Verification Extension to the JSON Meta Application Protocol (JMAP) Lets a JMAP mail server tell your mail client whether an S/MIME signature checked out, so the client does not have to. RFC 9422 SMTP LIMITS The LIMITS SMTP Service Extension How a mail server tells a client its limits up front, in the reply to EHLO, so the client stops tripping over them. RFC 9585 IMAP INPROGRESS IMAP Response Code for Command Progress Notifications A standard way for an IMAP server to tell a client how far along a slow command is, or just that it is still alive. RFC 9590 IMAP LIST-METADATA IMAP Extension for Returning Mailbox METADATA in Extended LIS Lets an email client ask for folder list and per-folder annotations in one IMAP command. RFC 9661 JMAP for Sieve The JSON Meta Application Protocol (JMAP) for Sieve Scripts How a JMAP client lists, uploads, activates and validates email-filtering Sieve scripts on a server. RFC 9698 IMAP JMAPACCESS The JMAPACCESS Extension for IMAP An IMAP extension that tells a logged-in client the same mail is also reachable through JMAP, and where. RFC 9749 JMAP Web Push VAPID Use of Voluntary Application Server Identification (VAPID) in JSON Meta Application Protocol (JMAP) Web Push How a JMAP server advertises the VAPID key that authenticates its Web Push notifications. RFC 1426 8BITMIME SMTP Service Extension for 8bit-MIMEtransport Lets mail servers send messages with non-ASCII characters without encoding. RFC 2086 IMAP4 ACL IMAP4 ACL extension Control who can access shared mailboxes through IMAP. RFC 2087 IMAP4 QUOTA IMAP4 QUOTA extension Let mail servers limit mailbox storage and report usage via IMAP RFC 2184 MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations Extending MIME to handle character sets, languages, and long parameter values. RFC 2303 Minimal PSTN address format in Internet Mail How to write a phone number as an email address for gateways RFC 5162 IMAP QRESYNC IMAP4 Extensions for Quick Mailbox Resynchronization Quickly resync a mailbox after disconnection without extra round trips. RFC 788 SMTP Simple Mail Transfer Protocol How mail computers hand email to each other reliably and efficiently. RFC 1148 X.400 and RFC 822 Mapping between X.400(1988) / ISO 10021 and RFC 822 How to translate between two incompatible email systems at a gateway. RFC 1528 Principles of Operation for the TPC.INT Subdomain: Remote Printing -- Technical Procedures Using email to send documents for remote printing via facsimile machines. RFC 1725 POP3 Post Office Protocol - Version 3 How a small computer fetches its waiting email from a server, one session at a time. RFC 2423 VPIM Voice Message MIME Sub-type Registration A MIME label to mark messages as voice mail. RFC 5337 Internationalized Delivery Status and Disposition Notifications Delivery status notifications that preserve non-ASCII email addresses. RFC 5504 UTF8SMTP downgrade Downgrading Mechanism for Email Address Internationalization Converting internationalized emails to ASCII when crossing non-UTF8-capable mail servers RFC 1563 text/enriched The text/enriched MIME Content-type Simple formatting markup for email that works on any system. RFC 1642 UTF-7 UTF-7 - A Mail-Safe Transformation Format of Unicode Encoding Unicode in 7-bit ASCII for email and old systems RFC 1806 Content-Disposition Communicating Presentation Information in Internet Messages: The Content-Disposition Header A header that tells email clients whether to show message parts inline or as downloadable attachments. RFC 1854 SMTP Pipelining SMTP Service Extension for Command Pipelining Send multiple email commands at once instead of waiting for each reply. RFC 2487 STARTTLS for SMTP SMTP Service Extension for Secure SMTP over TLS Upgrade SMTP connections to encryption mid-conversation. RFC 4550 Lemonade profile Internet Email to Support Diverse Service Environments (Lemonade) Profile A profile of IMAP and SMTP for clients with limited resources to send and receive email. RFC 5672 DKIM identifier update RFC 4871 DomainKeys Identified Mail (DKIM) Signatures -- Update Clarify what DKIM signatures tell you about who sent an email. RFC 5788 IMAP Keyword Registry IMAP4 Keyword Registry A registry and a registration process for the flags IMAP clients put on email messages. RFC 1460 POP3 Post Office Protocol - Version 3 A simple protocol for a mail client to pick up and delete the mail waiting for it on a server. RFC 1653 SMTP SIZE SMTP Service Extension for Message Size Declaration How an SMTP client can announce a message's size up front so the server can say no before the data is sent. RFC 1911 VPIM Voice Profile for Internet Mail A standard way for voice mail systems from different manufacturers to exchange messages using Internet email. RFC 2249 Mail Monitoring MIB A standardized way to monitor mail servers using SNMP. RFC 2422 ADPCM MIME Type Toll Quality Voice - 32 kbit/s ADPCM MIME Sub-type Registration A standardized MIME type for sending compressed voice audio in email. RFC 1114 PEM Part II Privacy enhancement for Internet electronic mail: Part II - certificate-based key management How to issue and trust encryption keys for secure email RFC 1115 PEM Part III Privacy enhancement for Internet electronic mail: Part III - algorithms, modes, and identifiers Algorithm identifiers and specifications for Privacy Enhanced Mail. RFC 1566 Mail Monitoring MIB Monitoring message delivery systems with SNMP gauges and counters RFC 2095 IMAP/POP AUTHorize IMAP/POP AUTHorize Extension for Simple Challenge/Response Prove your identity to IMAP/POP without sending passwords across the network RFC 2302 image/tiff Tag Image File Format (TIFF) - image/tiff MIME Sub-type Registration The standard MIME type for TIFF images sent over email and web protocols. RFC 2359 IMAP UIDPLUS IMAP4 UIDPLUS extension Three protocol optimizations that let email clients work more efficiently with IMAP servers. RFC 2424 Content Duration MIME Header Definition A MIME header that tells you how long audio or video plays. RFC 2632 S/MIME v3 Certificates S/MIME Version 3 Certificate Handling How S/MIME version 3 uses PKIX certificates to secure email messages and verify senders. RFC 2646 format=flowed The Text/Plain Format Parameter A way to write email that adapts to different screen widths. RFC 3009 parityfec MIME types Registration of parityfec MIME types Names for forward error correction streams in RTP RFC 3250 Tag Image File Format Fax eXtended (TIFF-FX) - image/tiff-fx MIME Sub-type Registration Official registration of a MIME type for fax images in TIFF-FX format. RFC 3431 Sieve relational Sieve Extension: Relational Tests Add comparison operators to the Sieve mail filtering language. RFC 3598 Sieve Subaddress Sieve Email Filtering -- Subaddress Extension Filter email by examining the user and detail parts of plus-addressed mailboxes. RFC 6577 Auth-Results SPF Update Authentication-Results Registration Update for Sender Policy Framework (SPF) Results Correct SPF result words in email authentication headers RFC 780 MTP Mail Transfer Protocol A protocol for transferring email between computers, with relay and multi-recipient support. RFC 5248 A Registry for SMTP Enhanced Mail System Status Codes An IANA registry so that new SMTP enhanced status codes stop colliding with each other. RFC 1081 POP3 Post Office Protocol: Version 3 A protocol for workstations to retrieve mail from a server. RFC 155 ARPA Network mailing lists A contact list for distributing the early RFCs to ARPANET sites RFC 221 Mail Box Protocol: Version 2 An early proposal for sending messages and documents across the ARPANET RFC 993 PCMAIL PCMAIL: A distributed mail system for personal computers A distributed mail system for personal computers with central storage and multiple client workstations. RFC 1486 Remote printing An Experiment in Remote Printing Using Internet email to send print jobs to fax machines by telephone number. RFC 1830 SMTP Large and Binary SMTP Service Extensions for Transmission of Large and Binary MIME Messages Send large emails and binary attachments without encoding overhead. RFC 6237 IMAP multimailbox SEARCH IMAP4 Multimailbox SEARCH Extension Search multiple mailboxes with a single command RFC 7817 Email TLS Identity Check Updated Transport Layer Security (TLS) Server Identity Check Procedure for Email-Related Protocols One consistent rule for how email clients decide that the server behind a TLS connection is really the one they meant to reach. RFC 1569 Principles of Operation for the TPC.INT Subdomain: Radio Paging -- Technical Procedures Using Internet email to send pages to radio pagers via phone numbers. RFC 772 MTP Mail Transfer Protocol A simple way to transfer messages between network computers, the predecessor to SMTP. RFC 1064 IMAP2 Interactive Mail Access Protocol: Version 2 A protocol for workstations to access mail stored on a remote server. RFC 1427 SMTP SIZE SMTP Service Extension for Message Size Declaration Lets clients declare message size so servers can reject too-large messages before they arrive. RFC 1544 Content-MD5 The Content-MD5 Header Field A message integrity check for MIME mail. RFC 2110 MHTML MIME E-mail Encapsulation of Aggregate Documents, such as HTML (MHTML) How to send web pages with pictures in email. RFC 3685 Sieve spamtest SIEVE Email Filtering: Spamtest and VirusTest Extensions Portable spam and virus scoring tests for email filters. RFC 4870 DomainKeys Domain-Based Email Authentication Using Public Keys Advertised in the DNS (DomainKeys) Sign email with public keys published in the DNS to prove it came from a domain. RFC 168 ARPA Network mailing lists Distribution mailing lists for early ARPANET documents. RFC 329 ARPA Network Mailing Lists Mailing lists for sending printed RFC documents to the early network. RFC 363 ARPA Network mailing lists Updated mailing lists for distributing network documents as the ARPANET grew. RFC 5738 IMAP UTF-8 IMAP Support for UTF-8 Extending IMAP to handle UTF-8 in usernames, mailbox names, and message headers RFC 1168 Intermail Intermail and Commercial Mail Relay services Bridging electronic mail between the Internet and commercial systems. RFC 1343 A User Agent Configuration Mechanism for Multimedia Mail Format Information A shared configuration file format that tells all mail clients which programs should handle which types of attachments. RFC 1344 Implications of MIME for Internet Mail Gateways How mail gateways can take advantage of MIME to improve service RFC 1428 Transition of Internet Mail from Just-Send-8 to 8bit-SMTP/MIME Moving email from informal 8-bit extensions to the standard MIME protocol RFC 1429 LISTSERV Listserv Distribute Protocol A protocol for bulk email delivery to large mailing lists RFC 1616 X.400(1988) for the Academic and Research Community in Europe A plan for deploying next-generation email across European research institutions. RFC 1711 Classifications in E-mail Routing A taxonomy of email routing strategies for distributed mail systems RFC 1741 BinHex MIME MIME Content Type for BinHex Encoded Files How to send Macintosh files as MIME email attachments using BinHex 4.0 encoding. RFC 1802 Project Long Bud Introducing Project Long Bud: Internet Pilot Project for the Deployment of X.500 Directory Information in Support of X.400 Routing A test run using X.500 directories to route X.400 email across the Internet. RFC 1895 CALS-1840 Content-type The Application/CALS-1840 Content-type Mailing military technical documents through email RFC 1927 Joke MIME Types Suggested Additional MIME Types for Associating Documents An April 1st parody of serious MIME type proposals. RFC 1947 Greek Email Encoding Greek Character Encoding for Electronic Mail Messages How to send email with Greek text and ensure it arrives correctly. RFC 1957 Some Observations on Implementations of the Post Office Protocol (POP3) Real-world variations in how mail servers and clients handle POP3. RFC 2442 Batch SMTP The Batch SMTP Media Type Encapsulate SMTP transactions as MIME objects for transport through non-SMTP networks. RFC 2503 MIME Types for Use with the ISO ILL Protocol A standard way to send library loan request forms by email RFC 2524 EMSD Neda's Efficient Mail Submission and Delivery (EMSD) Protocol Specification Version 1.3 Efficient mail submission and delivery for wireless and bandwidth-limited networks. RFC 2635 DON'T SPEW DON'T SPEW A Set of Guidelines for Mass Unsolicited Mailings and Postings (spam*) Why mass unsolicited email harms the Internet and how to handle it. RFC 2927 MIME Directory Profile for LDAP Schema A way to package LDAP schema definitions as email attachments. RFC 3073 Portable Font Resource (PFR) - application/font-tdpfr MIME Sub-type Registration Registers the MIME type for Portable Font Resource files. RFC 3240 DICOM MIME Type Digital Imaging and Communications in Medicine (DICOM) - Application/dicom MIME Sub-type Registration Registers the application/dicom media type for medical imaging data. RFC 3391 PWG multiplexed type The MIME Application/Vnd.pwg-multiplexed Content-Type A MIME type for packaging multi-component documents with interleaved parts RFC 3974 SMTP Operational Experience in Mixed IPv4/v6 Environments Keeping mail flowing when DNS has both old and new address formats. RFC 4047 FITS MIME Types MIME Sub-type Registrations for Flexible Image Transport System (FITS) Registering standard media types for astronomical data files RFC 4096 Email Subject Labels Policy-Mandated Labels Such as "Adv:" in Email Subject Headers Considered Ineffective At Best Why policy-mandated labels like Adv: in email subject lines don't work and what to do instead. RFC 4249 Implementer-Friendly Specification of Message and MIME-Part Header Fields and Field Components Guide for writing clear email header field specifications. RFC 4416 LEMONADE Goals Goals for Internet Messaging to Support Diverse Service Environments Design principles for mobile email across phones, networks, and media types RFC 4902 Integrity, Privacy, and Security in Open Pluggable Edge Services (OPES) for SMTP Applying Open Pluggable Edge Services to email and SMTP gateways. RFC 5616 IMAP streaming Streaming Internet Messaging Attachments Stream audio and video email attachments instead of downloading them fully. RFC 6109 Italian PEC La Posta Elettronica Certificata - Italian Certified Electronic Mail A government-backed certified email system with legal proof of delivery RFC 6471 DNSBL best practices Overview of Best Email DNS-Based List (DNSBL) Operational Practices How to run and use DNS-based blocklists for email reputation RFC 6477 MMHS header fields Registration of Military Message Handling System (MMHS) Header Fields for Use in Internet Mail Header fields for military message services in Internet email. RFC 6758 MT-PRIORITY tunneling Tunneling of SMTP Message Transfer Priorities How to preserve email priority through mail servers that don't understand priority. RFC 7017 IMAP Access to IETF Email List Archives Browse IETF mailing list archives with your email client RFC 7103 Advice for Safe Handling of Malformed Messages Practical guidance for handling email messages that don't follow the rules. RFC 7259 Jabber-ID Header The Jabber-ID Header Field Add your XMPP chat address to an email message header. RFC 7281 Authentication-Results Registration for S/MIME Signature Verification Reporting S/MIME signature verification results in email headers RFC 7444 SIO-Label Security Labels in Internet Email A header field to mark email messages with sensitivity information for display and policy handling. RFC 7681 Email Exchange of Secondary School Transcripts A secure way for students to email their school transcripts to colleges and employers RFC 7912 Message Authorizing Email Header Field and Its Use for the Draft and Release Procedure A header field for military message approval and secure release RFC 8494 MULE Multicast Email (MULE) over Allied Communications Publication (ACP) 142 Send email to many receivers at once over bandwidth-limited radio networks. RFC 8904 DNSWL DNS Whitelist (DNSWL) Email Authentication Method Extension Recording whether a sender's IP address is on a trusted whitelist. RFC 9979 IMAP/JMAP keywords Registration of Further IMAP/JMAP Keywords and Mailbox Name Attributes Standardized labels for email features that were already in wide use RFC 196 Mail Box Protocol A network drop box for files to be printed or processed. RFC 984 PCMAIL PCMAIL: A distributed mail system for personal computers A distributed mail system architecture for personal computers with a central repository RFC 989 PEM Privacy enhancement for Internet electronic mail: Part I: Message encipherment and authentication procedures The first Privacy-Enhanced Mail RFC: end-to-end encryption and sender authentication for Internet email, with no changes to mail relays. RFC 5008 Suite B S/MIME Suite B in Secure/Multipurpose Internet Mail Extensions (S/MIME) Using NSA-approved cryptography for secure email RFC 1529 Principles of Operation for the TPC.INT Subdomain: Remote Printing -- Administrative Policies Rules for running shared fax service through the Internet. RFC 1523 text/enriched The text/enriched MIME Content-type A simple format for sending formatted text in emails. RFC 1820 MIME UA Checklist Multimedia E-mail (MIME) User Agent Checklist A to-do list for testing whether an email client can handle multimedia attachments. RFC 9122 Sieve Actions Registry IANA Registry for Sieve Actions A new IANA registry that lists every Sieve mail-filtering action and how it interacts with the others. RFC 1040 PEM Privacy enhancement for Internet electronic mail: Part I: Message encipherment and authentication procedures The first part of a privacy enhancement system for email that encrypts and authenticates messages. RFC 1154 Encoding Header Encoding header field for internet messages A header field for describing multi-part email messages and how to decode each part. RFC 1405 X.400 to Mail-11 Mapping between X.400(1984/1988) and Mail-11 (DECnet mail) How to translate messages between two different email systems RFC 5721 POP3 UTF-8 POP3 Support for UTF-8 Bringing international characters to the email retrieval protocol. RFC 5825 Downgraded EAI Display Displaying Downgraded Messages for Email Address Internationalization Showing international email addresses after they've been converted to ASCII. RFC 5983 Mailing Lists and Internationalized Email Addresses Handling international addresses in mailing list operations RFC 9091 DMARC PSD Experimental Domain-Based Message Authentication, Reporting, and Conformance (DMARC) Extension for Public Suffix Domains Extending DMARC policy to top-level and multi-part domains RFC 3462 multipart/report The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages A container for email reports mixing human and machine readable content. RFC 724 Proposed official standard for the format of ARPA Network messages Proposed official standard for the header format of ARPA Network messages (email). RFC 806 Proposed Federal Information Processing Standard: Specification for message format for computer based message systems A standard format for messages between different mail systems so they can understand each other. RFC 918 POP Post Office Protocol Simple protocol for workstations to fetch mail from a server RFC 1153 Digest Format Digest message format The standard format for bundling multiple email messages into a single digest. RFC 1204 MPP Message Posting Protocol (MPP) Protocol for personal computers to submit outgoing mail to a mail service host. RFC 1339 RMCP Remote Mail Checking Protocol Lightweight UDP-based protocol for checking if new mail has arrived. RFC 1845 SMTP Checkpoint/Restart SMTP Service Extension for Checkpoint/Restart Resume interrupted mail transfers without resending everything that arrived before the break. RFC 3183 Domain Security Services using S/MIME S/MIME security services at the domain boundary, not end-to-end. RFC 6541 DomainKeys Identified Mail (DKIM) Authorized Third-Party Signatures Authorizing third-party services to sign email with DKIM on a domain's behalf RFC 7508 Secure Headers Securing Header Fields with S/MIME Protecting email message headers with cryptographic signatures and encryption. RFC 9057 Author header field Email Author Header Field Preserving the original author when mailing lists modify the From field RFC 9078 Email Reaction Reaction: Indicating Summary Reaction to a Message Bringing social media style reactions to email messages RFC 9228 Delivered-To Delivered-To Email Header Field Email header field to record delivery addresses RFC 9477 CFBL address header Complaint Feedback Loop Address Header Automated feedback loop for email spam complaints without manual setup. RFC 1892 Multipart/Report The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages A standard MIME container for mail system reports such as delivery failure notices. RFC 7114 Creation of a Registry for smime-type Parameter Values A central registry for S/MIME content type labels. RFC 7107 Object Identifier Registry for the S/MIME Mail Security Working Group Who holds the S/MIME object identifier arc, what is already numbered inside it, and how new numbers get handed out. RFC 1872 MIME Multipart/Related The MIME Multipart/Related Content-type A MIME content-type for sending related parts that make sense only together. RFC 224 Comments on Mailbox Protocol Why small machines cannot run the mailbox protocol. RFC 456 Memorandum: Date change of mail meeting A rescheduled meeting to discuss network email protocols. RFC 469 Network mail meeting summary Summary of conclusions from the February 1973 Network Mail meeting at SRI-ARC RFC 498 On mail service to CCN Robert Braden explains UCLA's mail policy and proposes extensions to FTP mail. RFC 574 Announcement of a Mail Facility at UCSB Announcing network mail capability at a new server. RFC 577 Mail priority Argues for allowing users to assign priority levels to mail messages. RFC 706 On the junk mail problem An early call to filter unwanted messages on the ARPANET. RFC 720 Address Specification Syntax for Network Mail A richer syntax for specifying email addresses and mailing lists. RFC 751 Survey of FTP mail and MLFL A survey of how ARPANET FTP servers handled mail and an alternative mail command RFC 754 Out-of-net host addresses for mail How to address mail to hosts on networks other than the ARPANET. RFC 757 Suggested solution to the naming, addressing, and delivery problem for ARPANET message systems A brainstorm on the future of computer mail: names, addresses, and delivery systems. RFC 763 Role mailboxes Use role-based mail addresses so messages reach the current job holder, not a specific person. RFC 773 Comments on NCP/TCP mail service transition strategy Comments and detailed guidance on managing email during the protocol transition. RFC 786 Mail Transfer Protocol: ISI TOPS20 MTP-NIMAIL interface How MTP and NIMAIL exchange mail on ISI TOPS-20. RFC 805 Computer mail meeting notes How the Internet settled on hierarchical domain-based email addresses RFC 807 Multimedia mail meeting notes Meeting notes on connecting computers to send mixed-type messages in 1982. RFC 808 Summary of computer mail services meeting held at BBN on 10 January 1979 Summary of a 1979 meeting on unifying the chaotic state of ARPANET email. RFC 876 SMTP survey Survey of SMTP implementations A 1983 snapshot of how the Internet's mail servers handled the new protocol. RFC 886 Proposed standard for message header munging Rules for translating mail between systems with different message formats. RFC 910 Multimedia mail meeting notes Meeting notes on early multimedia email systems, 1984 RFC 915 Network mail path service A network service to find mail routes to non-Internet hosts. RFC 1082 POP3 Extensions Post Office Protocol: Version 3: Extended service offerings Add discussion group mailbox access to POP3 so one client can read both personal mail and shared group messages.