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Encyclopedia > MIME
The five-layer TCP/IP model
5. Application layer

DHCP · DNS · FTP · Gopher · HTTP · IMAP4 · IRC · NNTP · XMPP · POP3 · SIP · SMTP · SNMP · SSH · TELNET · RPC · RTCP · RTSP · TLS · SDP · SOAP · GTP · STUN · NTP · RIP · ... Look up mime in Wiktionary, the free dictionary. ... The TCP/IP model or Internet reference model, sometimes called the DoD model (DoD, Department of Defense), ARPANET reference model, is a layered abstract description for communications and computer network protocol design. ... The application layer is the seventh level of the seven-layer OSI model. ... (DHCP) is a set of rules used by a communications device such as a computer, router or network adapter to allow the device to request and obtain an IP address from a server which has a list of addresses available for assignment. ... It has been suggested that this article be split into multiple articles. ... This article is about the File Transfer Protocol standardised by the IETF. For other file transfer protocols, see File transfer protocol (disambiguation). ... Gopher is a distributed document search and retrieval network protocol designed for the Internet. ... Hypertext Transfer Protocol (HTTP) is a communications protocol used to transfer or convey information on the World Wide Web. ... The Internet Message Access Protocol (commonly known as IMAP or IMAP4, and previously called Internet Mail Access Protocol, Interactive Mail Access Protocol (RFC 1064), and Interim Mail Access Protocol[1]) is an application layer Internet protocol operating on port 143 that allows a local client to access e-mail on... “IRC” redirects here. ... The Network News Transfer Protocol or NNTP is an Internet application protocol used primarily for reading and posting Usenet articles, as well as transferring news among news servers. ... Jabber redirects here. ... In computing, local e-mail clients use the Post Office Protocol version 3 (POP3), an application-layer Internet standard protocol, to retrieve e-mail from a remote server over a TCP/IP connection. ... The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. ... The simple network management protocol (SNMP) forms part of the internet protocol suite as defined by the Internet Engineering Task Force (IETF). ... Secure Shell or SSH is a network protocol that allows data to be exchanged over a secure channel between two computers. ... For the packet switched network, see Telenet. ... Remote procedure call (RPC) is a protocol that allows a computer program running on one computer to cause a subroutine on another computer to be executed without the programmer explicitly coding the details for this interaction. ... RTP Control Protocol (RTCP) is a sister protocol of the Real-time Transport Protocol (RTP). ... The Real Time Streaming Protocol (RTSP), developed by the IETF and created in 1998 as RFC 2326, is a protocol for use in streaming media systems which allows a client to remotely control a streaming media server, issuing VCR-like commands such as play and pause, and allowing time-based... Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide secure communications on the Internet for such things as web browsing, e-mail, Internet faxing, instant messaging and other data transfers. ... Session Description Protocol (SDP), is a format for describing streaming media initialization parameters. ... A collection of decorative soaps used for human hygiene purposes. ... GPRS Tunneling Protocol (or GTP) is an IP based protocol used within GSM and UMTS networks. ... STUN (Simple Traversal of UDP over NATs) is a network protocol which helps many types of software and hardware receive UDP data properly through home broadband routers that use network address translation (NAT). ... The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. ... This article is chiefly about the Routing Information Protocol (RIP) for the Internet Protocol, but also discusses some other routing information protocols. ...

4. Transport layer
TCP · UDP · DCCP · SCTP · RTP · RSVP · IGMP · ICMP · ICMPv6 ·

PPTP · ... In computing and telecommunications, the transport layer is the second highest layer in the four and five layer TCP/IP reference models, where it responds to service requests from the application layer and issues service requests to the Internet layer. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ... The Datagram Congestion Control Protocol (DCCP) is a message-oriented transport layer protocol that is currently under development in the IETF. Applications that might make use of DCCP include those with timingconstraints on the delivery of data such that reliable in-order delivery, when combined with congestion control, is likely... In the field of computer networking, the IETF Signaling Transport (SIGTRAN) working group defined the Stream Control Transmission Protocol (SCTP) as a transport layer protocol in 2002. ... The Real-time Transport Protocol (or RTP) defines a standardized packet format for delivering audio and video over the Internet. ... The Resource ReSerVation Protocol (RSVP), described in RFC 2205, is a transport layer protocol designed to reserve resources across a network for an integrated services Internet. ... The Internet Group Management Protocol is a communications protocol used to manage the membership of Internet Protocol multicast groups. ... The Internet Control Message Protocol (ICMP) is one of the core protocols of the Internet protocol suite. ... The ICMP for IPv6 (Internet Control Message Protocol Version 6) is an integral part of the IPv6 architecture and must be completely supported by all IPv6 implementations. ... The Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual private networks. ...

3. Network/Internet layer
IP (IPv4 · IPv6) · OSPF · IS-IS · BGP · IPsec · ARP · RARP · ...
2. Data link layer
802.11 · Wi-Fi · WiMAX · ATM · DTM · Token ring · Ethernet · FDDI · Frame Relay · GPRS · EVDO · HSPA · HDLC · PPP · L2TP · ISDN · ...
1. Physical layer
Ethernet physical layer · Modems · PLC · SONET/SDH · G.709 · OFDM · Optical fiber · Coaxial cable · Twisted pair · ...
This box: view  talk  edit


Multipurpose Internet Mail Extensions (MIME) is an Internet Standard that extends the format of e-mail to support: The network layer is third layer out of seven in OSI model and it is the third layer out of five in TCP/IP model. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... Internet Protocol version 4 is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. ... Internet Protocol version 6 (IPv6) is a network layer protocol for packet-switched internetworks. ... The Open Shortest Path First (OSPF) protocol is a hierarchical interior gateway protocol (IGP) for routing in Internet Protocol, using a link-state in the individual areas that make up the hierarchy. ... Is Is is Yeah Yeah Yeahs third EP, to be released on July 24, 2007. ... The Border Gateway Protocol (BGP) is the core routing protocol of the Internet. ... IPsec (IP security) is a suite of protocols for securing Internet Protocol (IP) communications by authenticating and/or encrypting each IP packet in a data stream. ... In computer networking, the Address Resolution Protocol (ARP) is the standard method for finding a hosts hardware address when only its network layer address is known. ... Reverse Address Resolution Protocol (RARP) is a network layer protocol used to obtain an IP address for a given hardware address (such as an Ethernet address). ... This article does not cite any references or sources. ... IEEE 802. ... Official Wi-Fi logo Wi-Fi (pronounced wye-fye, IPA: ), also unofficially known as Wireless Fidelity, is a wireless technology brand owned by the Wi-Fi Alliance intended to improve the interoperability of wireless local area network products based on the IEEE 802. ... Official WiMax logo WiMAX, the Wireless Interoperability for Microwave Access, is a telecommunications technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. ... Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ... Dynamic synchronous Transfer Mode , or DTM for short, is a network protocol. ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... General Packet Radio Service (GPRS) is a Mobile Data Service available to users of Global System for Mobile Communications (GSM) and IS-136 mobile phones. ... Evolution-Data Optimized or Evolution-Data only, abbreviated as EV-DO or EVDO and often EV, is one telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. ... High-Speed Packet Access (HSPA) is a collection of mobile telephony protocols that extend and improve the performance of existing UMTS protocols. ... High-Level Data Link Control (HDLC) is a bit-oriented synchronous data link layer protocol developed by the International Organization for Standardization (ISO). ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... In computer networking, the Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). ... ISDN redirects here. ... This article does not cite any references or sources. ... IEEE photograph of a diagram with the original terms for describing Ethernet drawn by Robert M. Metcalfe around 1976. ... For other uses, see Modem (disambiguation). ... For other uses, see Power band. ... It has been suggested that this article be split into articles entitled Synchronous optical networking, SONET and Synchronous digital hierarchy. ... There are very few or no other articles that link to this one. ... Orthogonal Frequency-Division Multiplexing (OFDM) — essentially identical to Coded OFDM (COFDM) — is a digital multi-carrier modulation scheme, which uses a large number of closely-spaced orthogonal sub-carriers. ... Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. ... Coaxial Cable For the weapon, see coaxial weapon. ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... An Internet standard is a specification for an innovative internetworking technology or methodology, which the Internet Engineering Task Force (IETF) ratified as an open standard after the innovation underwent peer review. ... Electronic mail, abbreviated e-mail or email, is a method of composing, sending, and receiving messages over electronic communication systems. ...

  • text in character sets other than US-ASCII;
  • non-text attachments;
  • multi-part message bodies; and
  • header information in non-ASCII character sets.

Virtually all human-written Internet e-mail and a fairly large proportion of automated e-mail is transmitted via SMTP in MIME format. Internet e-mail is so closely associated with the SMTP and MIME standards that it is sometimes called SMTP/MIME e-mail.[1] A character encoding is a code that pairs a set of characters (such as an alphabet or syllabary) with a set of something else, such as numbers or electrical pulses. ... There are 95 printable ASCII characters, numbered 32 to 126. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. ...


The content types defined by MIME standards are also of importance outside of e-mail, such as in communication protocols like HTTP for the World Wide Web. HTTP requires that data be transmitted in the context of e-mail-like messages, even though the data may not actually be e-mail. For other senses of this word, see protocol. ... Hypertext Transfer Protocol (HTTP) is a communications protocol used to transfer or convey information on the World Wide Web. ... WWWs historical logo designed by Robert Cailliau The World Wide Web (commonly shortened to the Web) is a system of interlinked, hypertext documents accessed via the Internet. ...


MIME is specified in six RFCs : RFC 2045, RFC 2046, RFC 2047, RFC 4288, RFC 4289 and RFC 2077. In internetworking and computer network engineering, Request for Comments (RFC) documents are a series of memoranda encompassing new research, innovations, and methodologies applicable to Internet technologies. ...

Contents

Introduction

The basic Internet e-mail transmission protocol, SMTP, supports only 7-bit ASCII characters (see also 8BITMIME). This effectively limits Internet e-mail to messages which, when transmitted, include only the characters sufficient for writing a small number of languages, primarily English. Other languages based on the Latin alphabet typically include diacritics not supported in 7-bit ASCII, meaning text in these languages cannot be correctly represented in basic e-mail. Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ... 8BITMIME (RFC 1652) is an SMTP extension standardized in 1994 that facilitates the exchange of e-mail messages containing octets outside the seven-bit ASCII range. ... The English language is a West Germanic language that originates in England. ... The Latin alphabet, also called the Roman alphabet, is the most widely used alphabetic writing system in the world today. ... Example of a letter with a diacritic A diacritical mark or diacritic, also called an accent, is a small sign added to a letter to alter pronunciation or to distinguish between similar words. ...


MIME defines mechanisms for sending other kinds of information in e-mail, including text in languages other than English using character encodings other than ASCII as well as 8-bit binary content such as files containing images, sounds, movies, and computer programs. MIME is also a fundamental component of communication protocols such as HTTP, which requires that data be transmitted in the context of e-mail-like messages, even though the data might not fit this context. Mapping messages into and out of MIME format is typically done automatically by an e-mail client or by mail servers when sending or receiving Internet (SMTP/MIME) e-mail. A character encoding or character set (sometimes referred to as code page) consists of a code that pairs a sequence of characters from a given set with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the storage of text in computers... It has been suggested that this article or section be merged into image (disambiguation). ... Sound is a disturbance of mechanical energy that propagates through matter as a wave. ... This article is about motion pictures. ... A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ... HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ... This article does not cite any references or sources. ... A mail transfer agent or MTA (also called a mail transport agent, mail server, or a mail exchanger in the context of the Domain Name System) is a computer program or software agent that transfers electronic mail messages from one computer to another. ...


The basic format of Internet e-mail is defined in RFC 2822, which is an updated version of RFC 822. These standards specify the familiar formats for text e-mail headers and body and rules pertaining to commonly used header fields such as "To:", "Subject:", "From:", and "Date:". MIME defines a collection of e-mail headers for specifying additional attributes of a message including content type, and defines a set of transfer encodings which can be used to represent 8-bit binary data using characters from the 7-bit ASCII character set. MIME also specifies rules for encoding non-ASCII characters in e-mail message headers, such as "Subject:", allowing these header fields to contain non-English characters. In information technology, Header refers to supplemental data placed at the beginning of a block of data being stored or transmitted, which contain information for the handling of the data block. ...


MIME is extensible. Its definition includes a method to register new content types and other MIME attribute values.


The goals of the MIME definition included requiring no changes to pre-existing e-mail servers, and allowing plain text e-mail to function in both directions with pre-existing clients. These goals are achieved by using additional RFC 822-style headers for all MIME message attributes and by making the MIME headers optional with default values ensuring a non-MIME message is interpreted correctly by a MIME-capable client. In addition, a simple MIME text message is likely to be interpreted correctly by a non-MIME client although it has e-mail headers the non-MIME client won't know how to interpret. Similarly, if the quoted printable transfer encoding (see below) is used, the ASCII part of the message will be intelligible to users with non-MIME clients.


MIME headers

MIME-Version

The presence of this header indicates the message is MIME-formatted. The value is typically "1.0" so this header appears as

 MIME-Version: 1.0 

It should be noted that implementers have attempted to change the version number in the past and the change had unforeseen results. It was decided at an IETF meeting[citation needed] to leave the version number as is, even though there have been many updates and versions of MIME. The Internet Engineering Task Force (IETF) is charged with developing and promoting Internet standards. ...


Content-Type

This header indicates the Internet media type of the message content, consisting of a type and subtype, for example An Internet media type,[1] originally called a MIME type after MIME and sometimes a Content-type after the name of a header in several protocols whose value is such a type, is a two-part identifier for file formats on the Internet. ...

 Content-Type: text/plain 

Through the use of the multipart type, MIME allows messages to have parts arranged in a tree structure where the leaf nodes are any non-multipart content type and the non-leaf nodes are any of a variety of multipart types. This mechanism supports: A tree structure is a way of representing the hierarchical nature of a structure in a graphical form. ...

  • simple text messages using text/plain (the default value for "Content-type:")
  • text plus attachments (multipart/mixed with a text/plain part and other non-text parts). A MIME message including an attached file generally indicates the file's original name with the "Content-disposition:" header, so the type of file is indicated both by the MIME content-type and the (usually OS-specific) filename extension
  • reply with original attached (multipart/mixed with a text/plain part and the original message as a message/rfc822 part)
  • alternative content, such as a message sent in both plain text and another format such as HTML (multipart/alternative with the same content in text/plain and text/html forms)
  • many other message constructs

An operating system (OS) is the software that manages the sharing of the resources of a computer. ... A filename extension is a suffix to the name of a computer file applied to show its format. ... HTML, short for Hypertext Markup Language, is the predominant markup language for web pages. ...

Content-Transfer-Encoding

In June 1992, MIME (RFC 1341, since obsoleted by RFC 2045) defined a set of methods for representing binary data in ASCII text format. The content-transfer-encoding: MIME header indicates the method that has been used. The RFC and the IANA's list of transfer encodings define the following values, which are not case sensitive: 1992 was a leap year starting on Wednesday. ...

  • Suitable for use with normal SMTP:
    • 7bit — up to 998 octets per line of the code range 1..127 with CR and LF (codes 13 and 10 respectively) only allowed to appear as part of a CRLF line ending. This is the default value.
    • quoted-printable — used to encode arbitrary octet sequences into a form that satisfies the rules of 7bit. Designed to be efficient and mostly human readable when used for text data consisting primarily of US-ASCII characters but also containing a small proportion of bytes with values outside that range.
    • base64 — used to encode arbitrary octet sequences into a form that satisfies the rules of 7bit. Has a fixed overhead and is intended for non text data and text that is not ASCII heavy.
  • Suitable for use with SMTP servers that support the 8BITMIME SMTP extension:
    • 8bit — up to 998 octets per line with CR and LF (codes 13 and 10 respectively) only allowed to appear as part of a CRLF line ending.
  • Suitable only for use with SMTP servers that support the BINARYMIME SMTP extension (RFC 3030):
    • binary — any sequence of octets.

There is no encoding defined which is explicitly designed for sending arbitrary binary data through SMTP transports with the 8BITMIME extension. Thus base64 or quoted-printable (with their associated inefficiency) must sometimes still be used. This restriction does not apply to other uses of MIME such as Web Services with MIME attachments or MTOM Quoted-printable is an encoding using ASCII characters for non-ASCII text. ... Base64 is a positional notation using a base of 64. ... 8BITMIME (RFC 1652) is an SMTP extension standardized in 1994 that facilitates the exchange of e-mail messages containing octets outside the seven-bit ASCII range. ... Extended SMTP (ESMTP) is a definition of protocol extensions to the Simple Mail Transfer Protocol standard. ... MTOM MTOM is the W3C Message Transmission Optimization Mechanism, A method of efficiently sending binary data to and from web services See WC3 Reference Category: ...


Encoded-Word

Since RFC 2822, message header names and values are always ASCII characters; values that contain non-ASCII data must use the MIME encoded-word syntax (RFC 2047) instead of a literal string. This syntax uses a string of ASCII characters indicating both the original character encoding (the "charset") and the content-transfer-encoding used to map the bytes of the charset into ASCII characters.


The form is: "=?charset?encoding?encoded text?=".

  • charset may be any character set registered with IANA. Typically it would be the same charset as the message body.
  • encoding can be either "Q" denoting Q-encoding that is similar to the quoted-printable encoding, or "B" denoting base64 encoding.
  • encoded text is the Q-encoded or base64-encoded text.

Difference between Q-encoding and quoted-printable The Internet Assigned Numbers Authority (IANA) is the entity that oversees global IP address allocation, DNS root zone management, and other Internet protocol assignments. ... Quoted-printable is an encoding using ASCII characters for non-ASCII text. ... Base64 is a positional notation using a base of 64. ...


The ASCII codes for the question mark (?) and equals sign may not be represented directly as they are used to delimit the encoded-word. The ASCII code for space may not be represented directly because it could cause older parsers to split up the encoded word undesirably. To make the encoding smaller and easier to read the underscore is used to represent the ASCII code for space creating the side effect that underscore cannot be represented directly. Use of encoded words in certain parts of headers imposes further restrictions on which characters may be represented directly.


For example,


Subject: =?utf-8?Q?=C2=A1Hola,_se=C3=B1or!?=


is interpreted as "Subject: ¡Hola, señor!".


The encoded-word format is not used for the names of the headers (for example Subject). These header names are always in English in the raw message. When viewing a message with a non-English e-mail client, the header names are usually translated by the client.


Multipart Messages

A MIME multipart message contains a boundary in the "Content-type:" header; this boundary, which must not occur in any of the parts, is placed between the parts, and at the beginning and end of the body of the message, as follows: Delimiters are marks which are used to seperate subfields of data. ...

 MIME-version: 1.0 Content-type: multipart/mixed; boundary="frontier" This is a multi-part message in MIME format. --frontier Content-type: text/plain This is the body of the message. --frontier Content-type: application/octet-stream Content-transfer-encoding: base64 PGh0bWw+CiAgPGhlYWQ+CiAgPC9oZWFkPgogIDxib2R5PgogICAgPHA+VGhpcyBpcyB0aGUg Ym9keSBvZiB0aGUgbWVzc2FnZS48L3A+CiAgPC9ib2R5Pgo8L2h0bWw+Cg== --frontier-- 

Each part consists of its own content header (zero or more Content- header fields) and a body. Multipart content can be nested. The content-transfer-encoding of a multipart type must always be "7bit", "8bit" or "binary" to avoid the complications that would be posed by multiple levels of decoding. The multipart block as a whole does not have a charset; non-ASCII characters in the part headers are handled by the Encoded-Word system, and the part bodies can have charsets specified if appropriate for their content-type.


Notes:

  • Before the first boundary is an area that is ignored by MIME compliant clients. This area is generally used to put a message to users of old non-MIME clients.
  • It is up to the sending mail client to choose a boundary string that doesn't clash with the body text. Typically this is done by inserting a large random string.

Multipart Subtypes

The MIME standard defines various multipart-message subtypes, which specify the nature of the message parts and their relationship to one another. The subtype is specified in the "Content-Type" header of the overall message. For example, a multipart MIME message using the digest subtype would have its Content-Type set as "multipart/digest".


The RFC initially defined 4 subtypes: mixed, digest, alternate and parallel. A minimally compliant application must support mixed and digest; other subtypes are optional. Additional subtypes, such as signed and form-data, have since been separately defined in other RFCs.


The following is a list of the most commonly used subtypes; it is not intended to be a comprehensive list.


Mixed

Multipart/mixed is used for sending files with different "Content-Type" headers inline (or as attachments). If sending pictures or other easily readable files, most mail clients will display them inline (unless otherwise specified with the "Content-disposition" header). Otherwise it will offer them as attachments. The default content-type for each part is "text/plain".


Defined in RFC 2046, Section 5.1.3


Digest

Multipart/digest is a simple way to send multiple text messages. The default content-type for each part is "message/rfc822".


Defined in RFC 2231, Section 5.1.5...


Alternative

The multipart/alternative subtype indicates that each part is an "alternative" version of the same (or similar) content, each in a different format denoted by its "Content-Type" header. The formats are ordered by how faithful they are to the original, with the least faithful first and the most faithful last. Systems can then choose the "best" representation they are capable of processing; in general, this will be the last part that the system can understand, although other factors may affect this.


Since a client is unlikely to want to send a version that is less faithful than the plain text version this structure places the plain text version (if present) first. This makes life easier for users of clients that do not understand multipart messages.


Most commonly multipart/alternative is used for email with two parts, one plain text (text/plain) and one HTML (text/html). The plain text part provides backwards compatibility while the HTML part allows use of formatting and hyperlinks. Most email clients offer a user option to prefer plain text over HTML; this is an example of how local factors may affect how an application chooses which "best" part of the message to display.


While it is intended that each part of the message represent the same content, it is not enforced in any way. At one time, anti-spam filters would only examine the text/plain part of a message, because it is easier to parse than the text/html part. But spammers eventually took advantage of this, creating messages with an innocuous-looking text/plain part and advertising in the text/html part. Anti-spam software eventually caught up on this trick, penalizing messages with very different text in a multipart/alternative message. E-mail spam, also known as bulk e-mail or junk e-mail is a subset of spam that involves sending nearly identical messages to numerous recipients by e-mail. ... This article is about spam, the abuse of electronic communications media to send unsolicited bulk messages. ...


Defined in RFC 2046, Section 5.1.4


Related

A multipart/related is used to indicate that message parts should not be considered individually but rather as parts of an aggregate whole. The message consists of a root part (by default, the first) which reference other parts inline, which may in turn reference other parts. Message parts are commonly referenced by the "Content-ID" part header. The syntax of a reference is unspecified and is instead dictated by the encoding or protocol used in the referring part.


One common usage of this subtype is to send a web page complete with images in a single message. The root part would contain the HTML document, and use image tags to reference images stored in the latter parts. HTML, short for Hypertext Markup Language, is the predominant markup language for web pages. ...


Defined in RFC 2387


Report

Multipart/report is a message type that contains data formatted for a mail server to read. It is split between a text/plain (or some other content/type easily readable) and a message/delivery-status, which contains the data formatted for the mail server to read.


Defined in RFC 3462


Signed

A multipart/signed message is used to attach a digital signature to a message. It has two parts, a body part and a signature part. The whole of the body part, including mime headers, is used to create the signature part. Many signature types are possible, like application/pgp-signature and application/x-pkcs7-signature. In cryptography, a digital signature or digital signature scheme is a type of asymmetric cryptography used to simulate the security properties of a signature in digital, rather than written, form. ...


Defined in RFC 1847, Section 2.1


Encrypted

A multipart/encrypted message has two parts. The first part has control information that is needed to decrypt the application/octet-stream second part.


Defined in RFC 1847, Section 2.2


Form Data

As its name implies, multipart/form-data is used to express values submitted through a form. Originally defined as part of HTML 4.0, it is most commonly used for submitting files via HTTP. HTML, short for Hypertext Markup Language, is the predominant markup language for web pages. ... HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ...


Defined in RFC 2388


Mixed-Replace (Experimental)

The content type multipart/x-mixed-replace was developed as part of a technology to emulate server push and streaming over HTTP. It has been suggested that this article or section be merged with Push media. ...


All parts of a mixed-replace message have the same semantic meaning. However, each part invalidates - "replaces" - the previous parts as soon as it is received completely. Clients should process the individual parts as soon as they arrive and should not wait for the whole message to finish.


Originally developed by Netscape, it is still supported by Mozilla, Firefox, Safari (but not in Safari on the iPhone) and Opera, but traditionally ignored by Microsoft.


See also

SOAP with Attachments (SwA) or MIME for Web Services refers to the method of using Web Services to send and receive files using a combination of SOAP and MIME, primarily over HTTP. Note that SwA is not a new specification, but rather a mechanism for using the existing SOAP and... DIME is a Microsoft-proposed internet standard for the transfer of binary and other encapsulated data over SOAP. According to the IETF web site, the standard has been withdrawn and never made RFC status. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... For other senses of this word, see protocol. ... The W3C defines a Web service (many sources also capitalize the second word, as in Web Services) as a software system designed to support interoperable Machine to Machine interaction over a network. ... S/MIME (Secure / Multipurpose Internet Mail Extensions) is a standard for public key encryption and signing of e-mail encapsulated in MIME. // S/MIME was originally developed by RSA Data Security Inc. ... A mailcap file can be used to find the correct program to open a file with, based on MIME information. ... Many e-mail clients are now able to use Unicode. ... An Internet media type,[1] originally called a MIME type after MIME and sometimes a Content-type after the name of a header in several protocols whose value is such a type, is a two-part identifier for file formats on the Internet. ...

References

RFC 1847 
Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted
RFC 2045 
MIME Part One: Format of Internet Message Bodies.
RFC 2046 
MIME Part Two: Media Types. N. Freed, Nathaniel Borenstein. November 1996.
RFC 2047 
MIME Part Three: Message Header Extensions for Non-ASCII Text. Keith Moore. November 1996.
RFC 4288 
MIME Part Four: Media Type Specifications and Registration Procedures.
RFC 4289 
MIME Part Four: Registration Procedures. N. Freed, J. Klensin. December 2005.
RFC 2049 
MIME Part Five: Conformance Criteria and Examples. N. Freed, N. Borenstein. November 1996.
RFC 2231 
MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations. N. Freed, K. Moore. November 1997.
RFC 2387 
The MIME Multipart/Related Content-type
RFC 1521 
Mechanisms for Specifying and Describing the Format of Internet Message Bodies

Nathaniel Borenstein is one of the original designers of the MIME protocol for sending multimedia Internet electronic mail. ... Keith Moore (born 12 October 1960) is the author and co-author of several IETF RFCs related to the MIME and SMTP protocols for electronic mail, among others: RFC 1870, defining a mechanism to allow SMTP clients and servers to avoid transferring messages so large that they will be rejected...

External links


  Results from FactBites:
 
RFC 2045 (rfc2045) - Multipurpose Internet Mail Extensions (MIME) Part One (8084 words)
Character Set The term "character set" is used in MIME to refer to a method of converting a sequence of octets into a sequence of characters.
MIME Header Fields MIME defines a number of new RFC 822 header fields that are used to describe the content of a MIME entity.
Content-Type Defaults Default RFC 822 messages without a MIME Content-Type header are taken by this protocol to be plain text in the US-ASCII character set, which can be explicitly specified as: Content-type: text/plain; charset=us-ascii This default is assumed if no Content-Type header field is specified.
MIME - Wikipedia, the free encyclopedia (1764 words)
MIME is specified in five parts starting with RFC 2045, RFC 2046, and RFC 2047.
MIME is also a fundamental component of communication protocols such as HTTP, which requires that data be transmitted in the context of e-mail-like messages, even though the data may not actually be e-mail.
MIME defines a collection of e-mail headers for specifying additional attributes of a message including content type, and defines a set of transfer encodings which can be used to represent 8-bit binary data using characters from the 7-bit ASCII character set.
  More results at FactBites »

 
 

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