Email is short for Electronic mail that you use when you write a letter to someone on the computer
For the former manufacturing conglomerate, see Email Limited.
The interface of an e-mail client, Thunderbird.Electronic mail, often abbreviated to e-mail, email, e-post or originally eMail, is a store-and-forward method of writing, sending, receiving and saving messages over electronic communication systems. The term "e-mail" (as a noun or verb) applies to the Internet e-mail system based on the Simple Mail Transfer Protocol, to network systems based on other protocols and to various mainframe, minicomputer, or internet by a particular systems vendor, or on the same protocols used on public networks.
Spelling
The spellings e-mail and email are both common. Several prominent journalistic and technical style guides recommend e-mail,[1][2][3][4] and the spelling email is also recognized in many dictionaries.[5][6][7][8][9] In the original RFC neither spelling is used; the service is referred to as mail, and a single piece of electronic mail is called a message.[10][11][12]
Newer RFCs[13] and IETF working groups[14] also use email. ARPAnet/DARPAnet users and early developers from Unix, CMS, AppleLink, eWorld, AOL, GEnie, and HotMail used eMail with the letter M capitalized. The authors of some of the original RFCs used eMail when giving their own addresses.[11][12]
[edit] Origin
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E-mail predates the inception of the Internet, and was in fact a crucial tool in creating the Internet.
MIT first demonstrated the Compatible Time-Sharing System (CTSS) in 1961.[15] It allowed multiple users to log into the IBM 7094[16] 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. Although the exact history is murky, among the first systems to have such a facility were SDC's Q32 and MIT's CTSS.
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 that the SAGE system had something similar some time before).
The ARPANET computer network made a large contribution to the development of e-mail. There is one report that indicates experimental inter-system e-mail transfers began shortly after its creation in 1969.[17] Ray Tomlinson initiated the use of the @ sign to separate the names of the user and their machine in 1971.[18] The ARPANET significantly increased the popularity of e-mail, and it became the killer app of the ARPANET.
[edit] Workings
[edit] Example
The diagram above shows a typical sequence of events [19] that takes place when Alice composes a message using her mail user agent (MUA). She types in, or selects from an address book, the e-mail address of her correspondent. She hits the "send" button.
Her MUA formats the message in Internet e-mail format and uses the Simple Mail Transfer Protocol (SMTP) to send the message to the local mail transfer agent (MTA), in this case smtp.a.org, run by Alice's Internet Service Provider (ISP).
The MTA looks at the destination address provided in the SMTP protocol (not from the message header), in this case bob@b.org. An Internet e-mail address is a string of the form localpart@exampledomain.com, which is known as a Fully Qualified Domain Address (FQDA). The part before the @ sign is the local part of the address, often the username of the recipient, and the part after the @ sign is a domain name. The MTA looks up this domain name in the Domain Name System to find the mail exchange servers accepting messages for that domain.
The DNS server for the b.org domain, ns.b.org, responds with an MX record listing the mail exchange servers for that domain, in this case mx.b.org, a server run by Bob's ISP.
smtp.a.org sends the message to mx.b.org using SMTP, which delivers it to the mailbox of the user bob.
Bob presses the "get mail" button in his MUA, which picks up the message using the Post Office Protocol (POP3).
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:
Alice or Bob may use a client connected to a corporate e-mail system, such as IBM Lotus Notes or Microsoft Exchange. These systems often have their own internal e-mail format and their clients typically communicate with the e-mail server using a vendor-specific, proprietary protocol. The server sends or receives e-mail via the Internet through the product's Internet mail gateway which also does any necessary reformatting. If Alice and Bob work for the same company, the entire transaction may happen completely within a single corporate e-mail system.
Alice may not have a MUA on her computer but instead may connect to a webmail service.
Alice's compu