Electronic mail, often abbreviated to e-mail, email, or simply mail, is a store-and-forward method of composing, sending, receiving and storing messages over electronic communication systems. Mozilla Thunderbird is a free, Open source, Cross-platform e-mail and News client developed by the Mozilla Foundation. Store and forward is a Telecommunications technique in which Information is sent to an intermediate station where it is kept and sent at a later time to the final A message in its most general meaning is an object of Communication. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical The term "e-mail" (as a noun or verb) applies both to the Internet e-mail system based on the Simple Mail Transfer Protocol (SMTP) and to X.400 systems, and to intranet systems allowing users within one organization to e-mail each other. The Internet is a global system of interconnected Computer networks Simple Mail Transfer Protocol ( SMTP) is a De facto standard for electronic mail (e-mail transmissions across the Internet. X400 is a suite of ITU-T Recommendations that define standards for Data Communication Networks for Message Handling Systems (MHS — more commonly known as " E-mail An intranet is a private computer network that uses Internet protocols and network connectivity to securely share any part of an organization's information or operational Intranets may use the Internet protocols or X. The Internet Protocol Suite (commonly TCP/IP) is the set of Communications protocols used for the Internet and other similar networks 400 protocols for internal e-mail service supporting workgroup collaboration. Collaboration is a recursive process where two or more people or organizations work together toward an intersection of common goals — for example an intellectual E-mail is often used to deliver bulk unsolicited messages, or "spam", but filter programs exist which can automatically delete some or most of these, depending on the situation. E-mail spam, also known as "bulk e-mail" or "junk e-mail" is a subset of spam that involves nearly identical messages sent to numerous recipients by
The spellings e-mail and email are both common. Several prominent journalistic and technical style guides recommend e-mail, and the spelling email is also recognized in many dictionaries. A style guide or style manual is a set of standards for design and writing of documents either for general use or for a specific publication or organization  In the original RFC definitions for the Internet's electronic mail system, neither spelling is used; the service is referred to as mail, and a single piece of electronic mail is called a message. In Computer network Engineering, a Request for Comments (RFC is a Memorandum published by the Internet Engineering Task Force (IETF describing  Some later RFCs use email. 
E-mail predates the inception of the Internet, and was in fact a crucial tool in creating the Internet. The Internet is a global system of interconnected Computer networks MIT first demonstrated the Compatible Time-Sharing System (CTSS) in 1961. This article is about the MIT Computation Center operating system  It allowed multiple users to log into the IBM 7094 from remote dial-up terminals, and to store files online on disk. This new ability encouraged users to share information in new ways. E-mail started in 1965 as a way for multiple users of a time-sharing mainframe computer to communicate. Time-sharing refers to sharing a computing resource among many users by multitasking. Mainframes (often colloquially referred to as Big Iron) are Computers used mainly by large organizations for critical applications typically bulk data Although the exact history is murky, among the first systems to have such a facility were SDC's Q32 and MIT's CTSS. System Development Corporation (SDC based in Santa Monica California, was arguably the world's first Computer software company
E-mail was quickly extended to become network e-mail, allowing users to pass messages between different computers by at least 1966 (it is possible the SAGE system had something similar some time before). The Semi-Automatic Ground Environment ( SAGE) was an automated control system for tracking and intercepting enemy Bomber aircraft used by NORAD from
The ARPANET computer network made a large contribution to the development of e-mail. The ARPANET ( Advanced Research Projects Agency Network) developed by ARPA of the United States Department of Defense, was the world's first operational A computer network is a group of interconnected Computers. Networks may be classified according to a wide variety of characteristics There is one report that indicates experimental inter-system e-mail transfers on it shortly after its creation in 1969.  Ray Tomlinson initiated the use of the @ sign to separate the names of the user and their machine in 1971. Raymond Samuel Tomlinson (born 1941) is a Programmer who implemented an Email system in 1971 on the ARPANet The typographic character @, the at sign, denotes a pan-lingual abbreviation of the word 'at'  The ARPANET significantly increased the popularity of e-mail, and it became the killer app of the ARPANET. The ARPANET ( Advanced Research Projects Agency Network) developed by ARPA of the United States Department of Defense, was the world's first operational A killer application (commonly shortened to killer app) in the jargon of computer programmers and video gamers has been used to refer to any Computer program
The diagram above shows a typical sequence of events that takes place when Alice composes a message using her mail user agent (MUA). An e-mail client, aka Mail User Agent (MUA aka e-mail reader is a frontend Computer program used to manage E-mail. She types in, or selects from an address book, the e-mail address of her correspondent. An e-mail address identifies a location to which E-mail messages can be delivered She hits the "send" button.
This sequence of events applies to the majority of e-mail users. However, there are many alternative possibilities and complications to the e-mail system:
It used to be the case that many MTAs would accept messages for any recipient on the Internet and do their best to deliver them. Such MTAs are called open mail relays. An open mail relay is an SMTP server configured in such a way that it allows anyone on the Internet to send E-mail through it not just mail destined This was important in the early days of the Internet when network connections were unreliable. If an MTA couldn't reach the destination, it could at least deliver it to a relay that was closer to the destination. The relay would have a better chance of delivering the message at a later time. However, this mechanism proved to be exploitable by people sending unsolicited bulk e-mail and as a consequence very few modern MTAs are open mail relays, and many MTAs will not accept messages from open mail relays because such messages are very likely to be spam. E-mail spam, also known as "bulk e-mail" or "junk e-mail" is a subset of spam that involves nearly identical messages sent to numerous recipients by
Note that the people, e-mail addresses and domain names in this explanation are fictional: see Alice and Bob. The names Alice and Bob are commonly used placeholders for archetypal characters in fields such as Cryptography and Physics.
The format of Internet e-mail messages is defined in RFC 2822 and a series of RFCs, RFC 2045 through RFC 2049, collectively called Multipurpose Internet Mail Extensions (MIME). In Computer network Engineering, a Request for Comments (RFC is a Memorandum published by the Internet Engineering Task Force (IETF describing Multipurpose Internet Mail Extensions ( MIME) is an Internet standard that extends the format of e-mail to support text in Character Although as of July 13, 2005 RFC 2822 is technically a proposed IETF standard and the MIME RFCs are draft IETF standards, these documents are the de facto standards for the format of Internet e-mail. Events 1174 - William I of Scotland, a key rebel in the Revolt of 1173-1174, is captured at Alnwick by forces loyal to Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Prior to the introduction of RFC 2822 in 2001 the format described by RFC 822 was the de facto standard for Internet e-mail for nearly two decades; it is still the official IETF standard. The IETF reserved the numbers 2821 and 2822 for the updated versions of RFC 821 (SMTP) and RFC 822, honoring the extreme importance of these two RFCs. RFC 822 was published in 1982 and based on the earlier RFC 733.
Internet e-mail messages consist of two major sections:
The header is separated from the body by a blank line. A signature block (often abbreviated as signature, sig block, sig file,.
The message header consists of fields, usually including at least the following:
Each header field has a name and a value. An e-mail address identifies a location to which E-mail messages can be delivered RFC 2822 specifies the precise syntax. Informally, the field name starts in the first character of a line, followed by a ":", followed by the value which is continued on non-null subsequent lines that have a space or tab as their first character. Field names and values are restricted to 7-bit ASCII characters. American Standard Code for Information Interchange ( ASCII) Non-ASCII values may be represented using MIME encoded words. Multipurpose Internet Mail Extensions ( MIME) is an Internet standard that extends the format of e-mail to support text in Character
Note that the "To" field in the header is not necessarily related to the addresses to which the message is delivered. The actual delivery list is supplied in the SMTP protocol, not extracted from the header content. The "To" field is similar to the greeting at the top of a conventional letter which is delivered according to the address on the outer envelope. Also note that the "From" field does not have to be the real sender of the e-mail message. It is very easy to fake the "From" field and let a message seem to be from any mail address. It is possible to digitally sign e-mail, which is much harder to fake. A digital signature or digital signature scheme is a type of asymmetric cryptography used to simulate the security properties of a handwritten Signature Some Internet service providers do not relay e-mail claiming to come from a domain not hosted by them, but very few (if any) check to make sure that the person or even e-mail address named in the "From" field is the one associated with the connection. An Internet service provider ( ISP, also called Internet access provider or IAP) is a company which primarily offers their customers access to the Internet Some Internet service providers apply e-mail authentication systems to e-mail being sent through their MTA to allow other MTAs to detect forged spam that might apparently appear to be from them. An Internet service provider ( ISP, also called Internet access provider or IAP) is a company which primarily offers their customers access to the Internet E-mail authentication is the effort to equip messages of the e-mail transport system with enough verifiable information so that recipients can recognize the nature of each incoming message
Many e-mail clients present "Bcc" (Blind carbon copy, recipients not visible in the "To" field) as a header field. Different protocols are used to deal with the "Bcc" field; at times the entire field is removed, whereas other times the field remains but the addresses therein are removed. Addresses added as "Bcc" are only added to the SMTP delivery list, and do not get included in the message data.
E-mail was originally designed for 7-bit ASCII. American Standard Code for Information Interchange ( ASCII) Much e-mail software is 8-bit clean but must assume it will be communicating with 7-bit servers and mail readers. Eight-bit clean describes a Computer system that correctly handles 8-bit character sets, such as the ISO 8859 series and the UTF-8 The MIME standard introduced character set specifiers and two content transfer encodings to enable transmission of non-ASCII data: quoted printable for mostly 7 bit content with a few characters outside that range and base64 for arbitrary binary data. Multipurpose Internet Mail Extensions ( MIME) is an Internet standard that extends the format of e-mail to support text in Character Quoted-printable, or QP encoding, is an encoding using printable characters (i The term Base64 refers to a specific MIME content transfer encoding. The 8BITMIME extension was introduced to allow transmission of mail without the need for these encodings but many mail transport agents still don't support it fully. 8BITMIME (RFC 1652 is an SMTP extension standardized in 1994 that facilitates the exchange of E-mail messages containing octets outside the seven-bit A mail transfer agent (MTA (also called a mail transport agent, message transfer agent, or smtpd (short for SMTP daemon) is a For international character sets, Unicode is growing in popularity. A character encoding consists of a code that pairs a sequence of characters from a given character set (sometimes incorrectly referred to as Code page In Computing, Unicode is an Industry standard allowing Computers to consistently represent and manipulate text expressed in most of the world's
Both plain text and HTML are used to convey e-mail. In Computing, plain text is a term used for an ordinary "unformatted" sequential file readable as textual material without much processing HTML, an initialism of HyperText Markup Language, is the predominant Markup language for Web pages It provides a means to describe the structure While text is certain to be read by all users without problems, there is a perception that HTML-based e-mail has a higher aesthetic value. HTML e-mail is the use of a Subset of HTML (often ill-defined to provide formatting and semantic markup capabilities in E-mail that are not Advantages of HTML include the ability to include inline links and images, set apart previous messages in block quotes, wrap naturally on any display, use emphasis such as underlines and italics, and change font styles. A block quotation also known as a long quotation, block quote or extract, is a Quotation in a written document set off from the main text An underline, also called an underscore, is one or more horizontal lines immediately below a portion of Writing. In Typography, italic type /ɪˈtælɪk/ or /aɪˈtælɪk/ refers to cursive Typefaces based on a stylized form of calligraphic Handwriting. In typography a font (also fount) is traditionally defined as a complete character set of a single size and style of a particular Typeface. HTML e-mail messages often include an automatically-generated plain text copy as well, for compatibility reasons. Disadvantages include the increased size of the email, privacy concerns about web bugs and that HTML email can be a vector for phishing attacks and the spread of malicious software. A Web bug is an object that is embedded in a Web page or E-mail and is usually invisible to the user but allows checking that a user has viewed the page or e-mail In the field of computer security phishing is the Criminally Fraudulent process of attempting to acquire sensitive information such as usernames Passwords Malware, a Portmanteau word from the words '''mal'''icious and soft'''ware''', is software designed to infiltrate or damage a computer system without 
Messages are exchanged between hosts using the Simple Mail Transfer Protocol with software programs called mail transport agents. Simple Mail Transfer Protocol ( SMTP) is a De facto standard for electronic mail (e-mail transmissions across the Internet. A mail transfer agent (MTA (also called a mail transport agent, message transfer agent, or smtpd (short for SMTP daemon) is a Users can download their messages from servers with standard protocols such as the POP or IMAP protocols, or, as is more likely in a large corporate environment, with a proprietary protocol specific to Lotus Notes or Microsoft Exchange Servers. In Computing, local E-mail clients use the Post Office Protocol version 3 ( POP3) an application-layer Internet standard protocol The Internet Message Access Protocol or IMAP is one of the two most prevalent Internet standard protocols for E-mail retrieval the other being POP3 A corporation is a separate legal entity usually used to conduct business Proprietary software is Computer software on which the producer has set restrictions on use private modification copying, or republishing. Lotus Notes is a Client-server, collaborative application developed and sold by IBM Software Group Microsoft Exchange Server is a Messaging and Collaborative software product developed by Microsoft.
Mail can be stored either on the client, on the server side, or in both places. A client is an application or system that accesses a remote service on another Computer system, known as a server, by way of a Network. A server is a Computer dedicated to providing one or more services over a computer network typically through a request-response routine Standard formats for mailboxes include Maildir and mbox. Maildir is a widely-used format for storing E-mail that does not require application-level File locking to maintain message integrity as messages are added moved mbox is a generic term for a family of related File formats used for holding collections of electronic mail messages Several prominent e-mail clients use their own proprietary format and require conversion software to transfer e-mail between them.
When a message cannot be delivered, the recipient MTA must send a bounce message back to the sender, indicating the problem. A bounce message, or (failed Delivery Status Notification (DSN message, aka Non-Delivery Report/Receipt (NDR, Non-Delivery Notification (NDN, or simply
Most, but not all, e-mail clients save individual messages as separate files, or allow users to do so. Different applications save e-mail files with different filename extensions. A filename extension is a suffix to the name of a Computer file applied to indicate the encoding convention ( File format) of its contents
Many observers bemoan the rise of flaming in written communications. Flaming occurs when one person sends an angry and/or antagonistic message. Flaming is assumed to be more common today because of the ease and impersonality of e-mail communications: confrontations in person or via telephone require direct interaction, where social norms encourage civility, whereas typing a message to another person is an indirect interaction, so civility may be forgotten.
Also known as "email fatigue", e-mail bankruptcy is when a user ignores a large number of e-mail messages after falling behind in reading and answering them. The reason for falling behind is often due to information overload and a general sense there is so much information that it is not possible to read it all. As a solution, people occasionally send a boilerplate message explaining that the email inbox is being cleared out. Stanford University law professor Lawrence Lessig is credited with coining this term, but he may only have popularized it. Leland Stanford Junior University, commonly known as Stanford University or simply Stanford, is a private Research university located in Lawrence Lessig (born June 3 1961) is an American academic and political activist 
E-mail was widely accepted by the business community as the first broad electronic communication medium and was the first ‘e-revolution’ in Business communication. E-mail is very simple to understand and like postal mail, e-mail solves two basic problems of communication. LAN based email is also an emerging form of usage for business. It not only allows the business user to download mail when offline, it also provides the small business user to have multiple users email ID's with just one email connection.
Much of the business world relies on communication between individuals who are physically distant from one another; organizing and participating in an in-person meeting can be time-consuming and expensive. E-mail provides a near-instantaneous exchange of information at little cost. Teleconferencing bridges physical distance, but the logistics of gathering people together at the same time remains. Teleconference is the live exchange and mass articulation of Information among persons and machines remote from one another but linked by a Telecommunications system
For real time communication, participants generally have to be working on the same schedule. They need to be at the same place at the same time and spend the same amount of time on the same information.
E-mail allows each participant to decide when and how they will process the information.
Most business professionals today spend between 20% and 50% of their working time using e-mail: reading, ordering, sorting, ‘re-contextualizing’ fragmented information and of course writing e-mail. Use of e-mail is increasing, due to trends of globalization—distribution of organizational divisions, outsourcing, among others. E-mail can lead to some well-known problems:
Despite these disadvantages, and despite the availability of other tools, e-mail-based communication is still the most widely used written medium in businesses.
A December 2007 New York Times blog post described E-mail as "a $650 Billion Drag on the Economy", and the New York Times reported in April 2008 that "E-MAIL has become the bane of some people’s professional lives" due to information overload, yet "none of [the current wave of high-profile Internet startups focused on email] really eliminates the problem of e-mail overload because none helps us prepare replies". 
Technology investors reflect similar concerns. 
The usefulness of e-mail is being threatened by four phenomena: e-mail bombardment, spamming, phishing and e-mail worms. In Internet usage an e-mail bomb is a form of net abuse consisting of sending huge volumes of e-mail to an address in an attempt to overflow the mailbox or E-mail spam, also known as "bulk e-mail" or "junk e-mail" is a subset of spam that involves nearly identical messages sent to numerous recipients by In the field of computer security phishing is the Criminally Fraudulent process of attempting to acquire sensitive information such as usernames Passwords A computer worm is a self-replicating Computer program. It uses a network to send copies of itself to other nodes (computer terminals on the network and it may do so without
Spamming is unsolicited commercial e-mail. Because of the very low cost of sending e-mail, spammers can send hundreds of millions of e-mail messages each day over an inexpensive Internet connection. Hundreds of active spammers sending this volume of mail results in information overload for many computer users who receive voluminous unsolicited email each day. Information overload refers to excess amounts of information being provided making the processing and absorbing tasks very difficult for the individual because we cannot see the validity
E-mail worms use e-mail as a way of replicating themselves into vulnerable computers. Although the first e-mail worm affected UNIX computers, the problem is most common today on the more popular Microsoft Windows operating system. The Morris worm or Internet worm was one of the first Computer worms distributed via the Internet; it is considered the first worm and was certainly the Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft.
The combination of spam and worm programs results in users receiving a constant drizzle of junk e-mail, which reduces the usefulness of e-mail as a practical tool.
A number of anti-spam techniques mitigate the impact of spam. To prevent E-mail spam, both end users and administrators of e-mail systems use various anti-spam techniques. In the United States, U.S. Congress has also passed a law, the Can Spam Act of 2003, attempting to regulate such e-mail. The United States of America —commonly referred to as the The United States Congress is the bicameral Legislature of the federal government of the United States of America, consisting of two houses The CAN-SPAM Act of 2003 ( 15 USC 7701 et seq Public Law No 108-187 was S Australia also has very strict spam laws restricting the sending of spam from an Australian ISP, but its impact has been minimal since most spam comes from regimes that seem reluctant to regulate the sending of spam.
E-mail privacy, without some security precautions, can be compromised because:
There are cryptography applications that can serve as a remedy to one or more of the above. Cryptography (or cryptology; from Greek grc κρυπτός kryptos, "hidden secret" and grc γράφω gráphō, "I write" For example, Virtual Private Networks or the Tor anonymity network can be used to encrypt traffic from the user machine to a safer network while GPG, PGP or S/MIME can be used for end-to-end message encryption, and SMTP STARTTLS or SMTP over Transport Layer Security/Secure Sockets Layer can be used to encrypt communications for a single mail hop between the SMTP client and the SMTP server. Tor ( The Onion Router) is a Free software implementation of second-generation Onion routing – a system enabling its users to communicate anonymously GNU Privacy Guard ( GnuPG or GPG) is a replacement for the PGP suite of cryptographic software Pretty Good Privacy (PGP is a Computer program that provides Cryptographic Privacy and Authentication. S/MIME ( Secure / Multipurpose Internet Mail Extensions) is a standard for Public key Encryption and signing of E-mail encapsulated Transport Layer Security ( TLS) and its predecessor Secure Sockets Layer ( SSL) are Cryptographic protocols that provide secure
Additionally, many mail user agents do not protect logins and passwords, making them easy to intercept by an attacker. An e-mail client, aka Mail User Agent (MUA aka e-mail reader is a frontend Computer program used to manage E-mail. Encrypted authentication schemes such as SASL prevent this. Simple Authentication and Security Layer ( SASL) is a Framework for Authentication and Data security in Internet protocols It decouples
Finally, attached files share many of the same hazards as those found in peer-to-peer filesharing. For other uses of the term see Peer-to-peer (disambiguation For peer-to-peer networks used for file sharing see File sharing Attached files may contain trojans or viruses. This article refers to a form of Malware in computing terminology A computer virus is a Computer program that can copy itself and infect a computer without permission or knowledge of the user
The original SMTP mail service provides limited mechanisms for tracking a sent message, and none for verifying that it has been delivered or read. It requires that each mail server must either deliver it onward or return a failure notice ("bounce message"), but both software bugs and system failures can cause messages to be lost. To remedy this, the IETF introduced Delivery Status Notifications (delivery receipts) and Message Disposition Notifications (return receipts); however, these are not universally deployed in production. A bounce message, or (failed Delivery Status Notification (DSN message, aka Non-Delivery Report/Receipt (NDR, Non-Delivery Notification (NDN, or simply A return receipt is a postal service document confirming the arrival of a Message or Parcel at its intended destination
The US Government has been involved in e-mail in several different ways.
Starting in 1977, the US Postal Service (USPS) recognized the electronic mail and electronic transactions posed a significant threat to First Class mail volumes and revenue. Therefore, the USPS initiated an experimental e-mail service known as E-COM. Electronic messages would be transmitted to a post office, printed out, and delivered in hard copy form. In order to take advantage of the service, an individual had to transmit at least 200 messages. The delivery time of the messages was the same as First Class mail and cost 26 cents. The service was said to be subsidized and apparently USPS lost substantial money on the experiment. Both the US Postal Commission and the Federal Communications Commission opposed E-COM. The FCC concluded that E-COM constituted common carriage under its jurisdiction and the USPS would have to file a tariff. For other uses of this word see Tariff (disambiguation. A tariff is a tax imposed on goods when they are moved across a political boundary  Three years after initiating the service, USPS canceled E-COM and attempted to sell it off. 
Early on in the history of the ARPANet, there were multiple e-mail clients which had various, and at times, incompatible formats. The ARPANET ( Advanced Research Projects Agency Network) developed by ARPA of the United States Department of Defense, was the world's first operational For example, in the system Multics, the "@" sign meant "kill line" and anything after the "@" sign would be ignored.  The Department of Defense DARPA desired to have uniformity and interoperability for e-mail and therefore funded efforts to drive towards unified interoperable standards. The United States Department of Defense ( DOD or DoD) is the federal department charged with coordinating and supervising all agencies and functions of the government The Defense Advanced Research Projects Agency (DARPA is an agency of the United States Department of Defense responsible for the development of new Technology This led to David Crocker, John Vittal, Kenneth Pogran, and Austin Henderson publishing RFC 733, "Standard for the Format of ARPA Network Text Message" (Nov. 21, 1977), which was apparently not effective. In 1979, a meeting was held at BBN to resolve incompatibility issues. Jon Postel recounted the meeting in RFC 808, "Summary of Computer Mail Services Meeting Held at BBN on 10 January 1979" (March 1, 1982), which includes an appendix listing the varying e-mail systems at the time. Jonathan Bruce Postel (pəˈstɛl August 6 1943 – October 16 1998 made many significant contributions to the development of the Internet, particularly in the area This, in turn, lead to the release of David Crocker's RFC 822, "Standard for the Format of ARPA Internet Text Messages" (Aug. 13, 1982). 
The National Science Foundation took over operations of the ARPANet and Internet from the Department of Defense, and initiated NSFNet, a new backbone for the network. The National Science Foundation (NSF is a United States Government agency that supports fundamental Research and Education in all the non-medical The National Science Foundation Network ( NSFNET) was a major part of early 1990s Internet backbone. A part of the NSFNet AUP was that no commercial traffic would be permitted.  In 1988, Vint Cerf arranged for an interconnection of MCI Mail with NSFNET on an experimental basis. Vinton Gray "Vint" Cerf His contributions have been recognized repeatedly with honorary degrees and awards that include the National Medal of Technology, and The following year Compuserve e-mail interconnected with NSFNET. Within a few years the commercial traffic restriction was removed from NSFNETs AUP, and NSFNET was privatized.
In the late 1990s, the Federal Trade Commission grew concerned with fraud transpiring in e-mail, and initiated a series of procedures on SPAM, fraud, and phishing. The Federal Trade Commission ( FTC) is an independent agency of the United States government, established in 1914 by the Federal Trade Commission Act  In 2004, FTC jurisdiction over SPAM was codified into law in the form of the CAN SPAM Act.  Several other US Federal Agencies have also exercised jurisdiction including the Department of Justice and the Secret Service.