Dictionary:

e-mail

  (ē'māl')

1. A system for sending and receiving messages electronically over a computer network, as between personal computers.
2. A message or messages sent or received by such a system.

To send (a message) by such a system.

[E(LECTRONIC) MAIL.]

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The asynchronous transmission of messages by using computers and data-communication networks. Historically, electronic mail (or e-mail) referred to any of a number of technologies that allowed people to send documents to one another through electronic means. It was frequently used to describe both wirephoto [the precursor of the facsimile (fax) machine] and telegraphy. Subsequently, usage of the term focused upon the narrower sense given above. See also Facsimile.

The use of electronic mail grew continuously until the late 1980s but never achieved widespread use outside of work groups or corporations. The limiting factor was the complicated addressing that had to be worked out before a message could be successfully transmitted.

There were two proposed methods to solve the problem of mail-system identification and routing. The Organization for International Standardization (ISO) formulated the X.400 standard, and the Internet community developed an extended use of the domain name system (DNS). Many impediments to the spread of X.400, such as high software costs and delays in standardization, caused the freely available DNS solution to become the de facto standard.

The DNS describes a worldwide distributed database in which each site maintains its own information about how to route messages to a computer within its administrative domain. A computer wishing to send a message to another asks the DNS for the routing information and uses the information returned to make the connection. This allows a person on virtually any online networking service to send mail to another person by giving only the personal identification and the e-mail system name of the recipient. See also Distributed systems (computers).

From the time the usage of the term narrowed to exclude facsimile until the early 1990s, generally only coded textual information could be transferred via e-mail. The transmission of nontextual data required special preprocessing, postprocessing, and prior arrangements between the sending and receiving parties. It was very difficult to make these kinds of transfers if the sending and receiving computers were different types.

This restriction was lifted with the adoption of the MIME (Multimedia Internet Mail Enhancements) standard. It described a way of encoding an arbitrary list of media types within a normal textual message in an operating-system-independent manner. Finally, different types of systems could send executable, sound, picture, movie, and other kinds of files to each other via e-mail. See also Multimedia technology.

The spread of electronic mail was also hampered by its lack of security. As mail was passed from one site to another closer to its destination, system administrators at each intermediate site could read messages. Also, the source of an e-mail message may be fairly easily forged to make it either untraceable or appear to come from another person. This limited the use of e-mail to so-called friendly applications. Public-key cryptography has been applied to e-mail messaging, notably in PEM (Privacy Enhanced Mail), in response to these security concerns. See also Computer security; Cryptography.

Since the communications speeds required for e-mail are quite modest, messages are sometimes transmitted by wireless means. Cell phones and personal digital assistants can send and receive e-mail through Earth-satellite relay. See also Internet; World Wide Web.

(Electronic-MAIL) The transmission of text messages and optional file attachments over a network. Within an enterprise, users can send mail to a single recipient or broadcast it to multiple users. Mail is sent to a simulated mailbox in the network mail server or host computer until it is examined and deleted. The mail program (e-mail client) in your computer queries the mail server every so many minutes and alerts you if new mail has arrived.

A Spelling Note...

In this Encyclopedia, we continue to use the dash in e-mail and other "e-" terms because the "e" pops out more readily, making it easier on the eye to discern.

The Messaging System and the Client

An e-mail system requires a messaging system, which provides the store and forward capability, such as the Internet's Simple Mail Transfer Protocol (SMTP). The mail client (mail program), such as Outlook or Eudora, provides the user interface with send and receive functions. The Web browser can also substitute for the mail client (see Internet e-mail service).

The Internet Changed It All

The Internet revolutionized e-mail by turning countless incompatible islands into one global system. Initially serving its own users, in the mid-1990s, the Internet began to act as a mail gateway between the major online services. It then became "the" messaging system for the planet. In the U.S., Internet mail is measured in the trillions of messages each year. See messaging system, instant messaging, e-mail attachment and self-destructing e-mail.

E-mail Vs. Fax

Fax documents are scanned images and are thus treated like pictures even if they contain only text. E-mail messages are raw ASCII text, which can be edited immediately in any mail program, text editor or your favorite word processor.

In order to edit the text in a fax, the images of the characters have to be turned into ASCII text by an OCR (optical character recognition) program, which is error prone. If all you want to do is read a message, either method works well. However, if to send text that will be edited and used again, e-mail is the better choice.

The First E-mail on the Internet

In 1971, the first e-mail was typed into the Teletype terminal connected to the Digital Equipment PDP-10 in the rear of the picture below. The message was transmitted via ARPAnet, the progenitor of the Internet, to the PDP-10 in front. Dan Murphy, a Digital engineer, took this photo in the Bolt, Beranek and Newman datacenter. See ARPAnet.

Could They Have Imagined Spam?

When they sent this first message in 1971, could they ever have imagined the billions of e-mails that would follow in the years to come?

Messages transmitted by computer over communications networks. The messages can be notes entered from an individual keyboard or electronic files stored in the computer or on a computer disk. They can be sent to one user at a time or broadcast to several users at the same time and usually take only a few minutes to arrive at their destination. Hence, e-mail is typically used to bypass regular postal service delivery (called snail mail by e-mail users) and to speed communications. Most computer networks have an e-mail system, although some are confined to a single computer network (as in an internal system within a small company), whereas others have gateways to other computer systems or networks, enabling the user to send messages anywhere to any system in the world. All on-line services and Internet service providers offer e-mail to subscribers. E-mail is fast, flexible, and reliable, and companies that are fully computerized make extensive use of it in the communication of internal and external messages, for relaying and confirming orders, sending press releases, announcing sales promotions, explaining price changes, updating scripts, confirming fund-raising pledges, offering camera-ready copy to publications, and a host of other business communications. An analysis in 1998 indicates that there are 25 million e-mail users sending 15 billion messages per year.

Document transmitted electronically from the user's computer or terminal to an information service. Accountants and their clients can take advantage of electronic mail to transmit essential messages. With electronic mail, each user in the system has a "mailbox," which receives, holds, and sends information to others. The information sent may be spreadsheets, reports, memos, and so forth.

Electronic mail, or e-mail, is a method of communicating whereby an individual uses a computer or other electronic device to compose and send a message to another individual. Messages may be sent through computer systems linked by a network, through modems using telephone lines, or, in some cases, through wireless transmissions.

While some systems provide links only within a company's particular e-mail system, the prevailing trend is for e-mail users to be able to send e-mail to anyone in the world. In order to send an e-mail message, each party must have an e-mail address. The address is composed of an identifying name, an @ sign, the name of the fileserver where the account is located, and a domain name. Typical domain names are com (commercial), gov (government), edu (schools), and org (organization). An example of an e-mail address would be marysmith@linc.lincoln.com. In order to send a message outside the company e-mail system, the complete address must be used.

Address book: Most electronic mail systems offer an address book feature. The address book provides a place to store e-mail addresses, which can often be complex and difficult to remember. The address book can also be used to develop mailing lists. For example, if six friends frequently communicate, a user might list all their addresses in a folder in the address book. The folder would have a name such as "My Friends." Then the user could quickly send a message to all six friends at one time by addressing the message to "My Friends" rather than to each individual user.

Attachments: While the majority of e-mail messages are composed of text, e-mail users are sending increasingly complex messages with accompanying attachments. Users can send documents by using an attachment feature of the e-mail package. The attachment feature allows the user to specify where an electronic file—such as a text document, a spreadsheet, or a graphics presentation—is located and then to send a copy by e-mail. Attachments can also be sent to a list of people in one e-mail message. This feature has greatly enhanced the ability of people at a distance to work together. For example, if two people are planning a presentation at a conference, they can attach outlines of the presentation as well as slides of the actual presentation and transmit them for revision or review.

Photographs can also be attached to e-mail messages, in the same way as another file can. One caution is that multimedia files including photos can be quite large and take a longer time to send. With the additional use of digital cameras and/or scanners, photographs that are valuable to business are easier to send than ever before.

Deleting a message: After reading an incoming e-mail message, the reader may decide that the message does not need to be saved. All e-mail systems have a feature to allow for quick deletion of messages. However, many systems convey the deleted message to a trash file that will allow the message to be recalled. To delete the message from the individual computer, the message in the trash file must also be deleted. Even after this double deletion, the message may still be accessible. Large computer systems periodically back up all mail, so the message may be floating around in the organization's computer memory backup for a much longer time.

Forwarding a message: At times, the reader of a message may decide to forward a message to a third party. The person sending e-mail has no control over what the receiver will do with the message. The receiver can easily forward the message to one individual or a list of individuals.

Replying to a message: If the reader wishes to respond to an e-mail message, the reply feature provides a quick way to answer the message without keying in the e-mail address of the person who sent it. There is a common e-mail faux pas, however, that should be avoided. If a message has been sent to a list and one reader replies to the person who sent the message by using the reply feature, that reply may be sent to everyone on the list. For example, a conference coordinator sends a reminder message to a list of 500 people who will be attending a conference. One of the respondents has a question about whether his or her registration has arrived and replies to the message using the reply feature. Since the original message was sent to a list, it is quite possible that using the reply feature will result in that individual's message being transmitted to all 500 people on the list instead of only to the original sender. This is a common violation of "netiquette," a term that refers to using courtesy on the Internet.

Netiquette: Using the correct etiquette helps people respond correctly in their environment. For example, eating peas with a knife, interrupting a speaker, and not introducing people are examples of poor etiquette. Poor etiquette can also exist in the electronic environment. A few things that could be considered violations of netiquette are flaming (sending an immediate, angry overreaction to an e-mail message), shouting (typing a message in all capital letters), forwarding personal messages without permission, and sending a personal message to an entire list. Other problems include preparing a list that includes individuals who have no interest in the topic and bombarding them with e-mail, sending e-mail messages that criticize others, and using emoticons (typed symbols to indicate expressions) in business e-mail. Just as an understanding of good manners helps one move effectively in society, so an understanding of netiquette helps one perform effectively in electronic communication.

Privacy of e-mail: One of the controversies surrounding electronic mail has been the issue of privacy. The term "mail" seems to imply the same safeguards that one has when using the U.S. Postal Service. These safeguards include the right to open your own mail and legal protection from those who would tamper with your mail. Electronic mail, however, may not include these safeguards.

Courts have upheld the right of corporations to review the e-mail of employees who use company resources such as hardware, software, and/or company time to compose and send e-mail messages. It is the court's position that a company has the right to read the e-mail of employees is especially strong for those companies who have an e-mail policy in place.

Employees should be judicious in their use of e-mail and should not put in electronic writing anything they would not write on paper for public distribution. Both individuals and companies have seen their e-mail communications come back to haunt them in the media and in court. For example, some plaintiffs in sexual harassment cases have used negative e-mail messages sent by company employees to establish the legal definition of a hostile working environment. Others have seen their e-mail admitted in court as proof of their beliefs and actions that may disagree with their sworn testimony.

Electronic mail policy: Many organizations have implemented e-mail policies in the workplace. A good policy clearly defines an employer's expectations about how e-mail should be used by employees. If personal e-mail is acceptable, conditions for its use are outlined in the policy. In addition, a process should be developed so employees can indicate their understanding of the e-mail policy in place.

Volume of electronic mail messages: A concern for many employees is the large number of e-mail messages that they receive and are expected to respond to on a daily basis. Some e-mail systems allow the sender to assign a priority rating to the message. In this way priority messages are flagged. Other systems rely on the subject line. For that reason, a concise subject line that clearly defines the message is an asset when a reader reviews the message. The subject line will help the reader decide when the message should be read. A message from an unknown sender with no subject line may not be evaluated very quickly.

Organizing electronic mail messages: As e-mail messages arrive, the reader can reply, forward, or delete them. The reader can also save or store messages. E-mail systems allow the reader to set up filters to organize incoming messages and folders to organize messages that should be stored. The reader then merely transfers the message to the appropriate folder. This action will clear the inbox of messages and provide a logical arrangement to locate messages by sender or by topic.

Response speed: Just as it is easier to send an e-mail message than to mail a letter or, in many cases, to attempt to phone someone, the amount of time allowed for a response has also decreased. While a letter may take two to three days to travel to its destination, an e-mail message is transmitted almost instantaneously. Few would expect an answer to a letter within a week of sending it. However, the tolerance for a slow e-mail response has dwindled. Seldom would a person sending an e-mail message expect to wait two to three days for a response. If the first e-mail message elicits no response, the sender may send follow-up messages or attempt some other means of communication if a timely response is not received.

Junk mail or spam: Junk mail, or spam, can arrive in the inbox in the form of chain letters, unsolicited advertisements, warnings (usually not founded in fact) about viruses or files, and other non-business information. The difference between the junk mail received via the U.S. Postal Service and the junk mail received through e-mail is that the former can be quickly discarded. The junk mail received via e-mail, however, is more difficult to get rid of and ties up the company's resources as well. Some corporations use procedures to block junk mail, or spam, from entering their e-mail systems. Some users find that friends or acquaintances can be the worst violators and are too willing to pass along unnecessary information they have found on the Internet.

Bibliography

Bicknell, David. (1999). "E-Mails That Could Cost Millions." Computer Weekly January 28:26.

Flynn, Nancy, and Flynn, Tom. (1998). Writing Effective E-Mail: Improving Your Electronic Communication. Menlo Park, CA: Crisp Publications.

Gleeson, Kerry. (1998). The High-Tech Personal Efficiency Program: Organizing Your Electronic Resources to Maximize Your Time and Efficiency. New York: Wiley.

Hartman, Diane B., and Nantz, Karen. (1996). The 3 R's of E-Mail: Risks, Rights, and Responsibilities. Menlo Park, CA: Crisp Publications.

Levin, John R., and Baroudi, Carol. (1997). E-Mail for Dummies, 2d ed. Foster City, CA: IDG Books Worldwide.

Mead, Hayden, and Hill, Brad. (1997). The On-Line/E-Mail Dictionary. New York: Berkley Publishing Group.

Overly, Michael R. (1999). E-Policy: How to Develop Computer, E-Policy, and Internet Guidelines to Protect YourCompany and Its Assets. AMACOM. Boulder, CO: Net Library, Inc.

Schwartz, Alan, and Ferguson, Paula. (1998). Managing Mailing Lists. Cambridge, England: O'Reilly and Associates, Inc.

Tuten, Tracy L., Urban, David J., and Gray, George. (1998). "Electronic Mail as Social Influence in Downsized Organizations." Human Resource Management 37(3,4):249-261.

[Article by: MARSHA L. BAYLESS]

(also written ‘e-mail’ and ‘E-mail’)

1. n. Electronic mail automatically passed through computer networks and/or via modems over common-carrier lines. Contrast snail-mail, paper-net, voice-net. See network address.

2. vt. To send electronic mail.

Oddly enough, the word emailed is actually listed in the OED; it means “embossed (with a raised pattern) or perh. arranged in a net or open work”. A use from 1480 is given. The word is probably derived from French émaillé (enameled) and related to Old French emmailleüre (network). A French correspondent tells us that in modern French, ‘email’ is a hard enamel obtained by heating special paints in a furnace; an ‘emailleur’ (no final e) is a craftsman who makes email (he generally paints some objects (like, say, jewelry) and cooks them in a furnace).

There are numerous spelling variants of this word. In Internet traffic up to 1995, ‘email’ predominates, ‘e-mail’ runs a not-too-distant second, and ‘E-mail’ and ‘Email’ are a distant third and fourth.

For more information on e-mail, visit Britannica.com.

The exact origins of electronic mail (or E-mail) are difficult to pinpoint, since there were many nearly simultaneous inventions, few of which were patented or widely announced. According to the standard account, computer-based messaging systems emerged alongside computer networks of the early 1960s, such as the pioneering "time-sharing" computer system installed on the campus of Massachusetts Institute of Technology (MIT). The MIT system and those that followed were intended to allow multiple users, sometimes spread out in various computer labs around campus, to access a central computer using keyboard and monitor terminals. The geographic dispersion of the terminals led to a desire for a convenient text message service. The resulting service at MIT was called "Mailbox," and may have been the first, but there were many similar programs written at about the same time.

By all accounts the first electronic mail program intended to transmit messages between two computers was written in 1972 by the engineer Ray Tomlinson of the company Bolt, Baranek and Newman [BBN]. MIT and BBN were both involved in the development of Advanced Research Projects Agency Network (ARPANET), the computer network that became the basis of the current Internet. In modifying Mailbox for this purpose, Tomlinson contributed the now-ubiquitous use of the "@" character to separate one's unique user name from the name of the host computer.

One of the well-known anecdotes of ARPANET lore is the way that the network, intended for research purposes, was regularly used for sending electronic mail messages. Indeed, electronic mail, along with the electronic bulletin board, became by far the most popular applications by the mid-1970s. As the volume of mail grew, programmers at various institutions around the United States and in Europe collaboratively improved the mail system and imposed technical standards to allow universal service.

It was estimated that less than ten thousand electronic mail messages were being transmitted per day in 1976, compared to about 140 million postal messages. By the end of the decade there were an estimated 400,000 unique electronic mailboxes across the country.

The relatively unplanned growth of the Internet (successor to ARPANET) makes it difficult to track the diffusion of electronic mail usage after the 1970s. In addition to the Internet, a host of mutually incompatible "dial-up" networks (such as Compuserve) existed, many of which also fostered the growth of E-mail usage. Many of these services were later absorbed into the Internet.

E-mail gained many new users as universities began making Internet service available to most students, and as corporations such as IBM encouraged its use on private networks by managers and executives. By the 1990s, E-mail came to refer only to electronic messaging via the Internet, which had now linked most of the previously separate computer networks in the United States.

Like the personal computer itself, E-mail usage by businesses became common several years before individuals began using it at home. Yet by the late 1990s, approximately forty percent of all American householders owned a computer, and twenty-six percent of those families had Internet access. An estimated 81 million E-mail users generated 3.4 trillion messages in 1998.

Bibliography

Abbate, Janet. Inventing the Internet. Boston: MIT Press, 1999.

—David Morton

As part of the revolution in high-tech communications, electronic mail, or E-mail, has soared in popularity since appearing in the mid-1980s. Over 40 million U.S. residents now regularly "E-mail" each other by computer. Faster and cheaper than traditional mail, this correspondence is commonly sent over office networks, through national services such as CompuServe Incorporated and MCI Mail, and across the global computer network known as the Internet. It is, however, less secure than traditional mail, even though federal law protects E-mail from unauthorized tampering and interception. Under the Electronic Communications Privacy Act of 1986 (ECPA) (Pub. L. No. 99-508, Oct. 21, 1986, 100 Stat. 1848), third parties are forbidden to read private E-mail. However, a loophole in the ECPA that allows employers to read their workers' E-mail has proved especially controversial. This has provoked several lawsuits and produced legislative and extralegal proposals to increase E-mail privacy.

Congress meant to increase privacy by passing the ECPA. Lawmakers took note of increasingly popular communications devices that were readily susceptible to eavesdropping— cellular telephones, pagers, satellite dishes, and E-mail. The law updated existing federal criminal codes in order to qualify these emerging technologies for constitutional protection under the Fourth Amendment. In the case of E-mail, Congress gave it most of the protection already accorded by law to traditional mail. Just as postal employees cannot divulge information about private mail to third parties, neither can E-mail services. The law provides criminal and civil penalties for violators: In cases of third-party interception, it establishes fines of up to $5,000 and prison sentences of up to six months. In cases of industrial espionage— where privacy is invaded for purposes of commercial advantage, malicious destruction, or private commercial gain — it establishes fines of up to $250,000 and prison sentences of up to one year. As with traditional mail, law enforcement agencies can seize E-mail as evidence in criminal investigations, and litigants can subpoena it in civil lawsuits.

To protect against disclosure of private or sensitive information, some attorneys advise employers and employees to exercise caution with E-mail, since it can be subpoenaed. Some experts have advised users to delete their E-mail regularly, and even to avoid saving it in the first place. Still others advocate the use of encryption software, which scrambles messages and makes them unreadable without a digital password.

Click here to submit an acronym.

This article is about electronic mail. For the former manufacturing comglomerate, see Email Limited.

E-mail (short for electronic mail; often also abbreviated as e-mail, email or simply mail) is a store and forward method of composing, sending, storing, and receiving messages over electronic communication systems. 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. Often these workgroup collaboration organizations may use the Internet protocols or X.400 protocols for internal e-mail service. 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.

Spelling

Spelling of this term is disputed, and varies by field. While "e-mail" (with a hyphen) is used in journalism (such as by the CNN, BBC and New York Times), the computer industry primarily uses the spelling "email" (no hyphen).^[1] In particular, the original spelling is "email" (no hyphen), based on the technical roots of the term, as seen in the RFC documents for SMTP,^[2] POP^[3] and IMAP,^[4] which use "mail" or "email."

"E-mail" is capitalized at the beginning of a sentence and in headings.

Origin

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.^[5] It allowed multiple users to log into the IBM 7094^[6] 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 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^[7] 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.^[8] The ARPANET significantly increased the popularity of e-mail, and it became the killer app of the ARPANET.

Workings

Example

The diagram above shows a typical sequence of events 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.

1. 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).
2. 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.
3. 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.
4. smtp.a.org sends the message to mx.b.org using SMTP, which delivers it to the mailbox of the user bob.
5. 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's Lotus Notes or Microsoft's 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 computer may run its own MTA, so avoiding the transfer at step 1.
• Bob may pick up his e-mail in many ways, for example using the Internet Message Access Protocol, by logging into mx.b.org and reading it directly, or by using a webmail service.
• Domains usually have several mail exchange servers so that they can continue to accept mail when the main mail exchange server is not available.
• E-mail messages are not secure if e-mail encryption is not used correctly.

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. 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.

Note that the people, e-mail addresses and domain names in this explanation are fictional: see Alice and Bob.

Format

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). Although as of July 13 2005 (see [4]) 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. 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:

• Header — Structured into fields such as summary, sender, receiver, and other information about the e-mail
• Body — The message itself as unstructured text; sometimes containing a signature block at the end

The header is separated from the body by a blank line.

Header

The message header consists of fields, usually including at least the following:

• From: The e-mail address, and optionally name, of the sender of the message
• To: The e-mail address[es], and optionally name[s], of the message's recipient[s]
• Subject: A brief summary of the contents of the message
• Date: The local time and date when the message was written

Each header field has a name and a value. 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. Non-ASCII values may be represented using MIME encoded words.

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. 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. 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.

Other common header fields include (see RFC 4021 or RFC 2076 for more):

• Cc: carbon copy
• Bcc: Blind Carbon Copy
• Received: Tracking information generated by mail servers that have previously handled a message
• Content-Type: Information about how the message has to be displayed, usually a MIME type
• Reply-To: Address that should be used to reply to the sender.
• References: Message-ID of the message that this is a reply to, and the message-id of this message, etc.
• In-Reply-To: Message-ID of the message that this is a reply to.
• X-Face: Small icon.

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.

IANA maintains a list of standard header fields.

Body

Content encoding

E-mail was originally designed for 7-bit ASCII. Much e-mail software is 8-bit clean but must assume it will be communicating with 7-bit servers and mail readers. 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. 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. For international character sets, Unicode is growing in popularity.

Plain Text and HTML

Both plain text and HTML are used to convey e-mail. 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. [5] 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. 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.[6]

Servers and client applications

Messages are exchanged between hosts using the Simple Mail Transfer Protocol with software programs called mail transport agents. 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.

Mail can be stored either on the client, on the server side, or in both places. Standard formats for mailboxes include Maildir and mbox. 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.

Filename extensions

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.

.eml

This is the default e-mail extension for Mozilla Thunderbird and Windows Mail. It is used by Microsoft Outlook Express.

.emlx

Used by Apple Mail.

.msg

Used by Microsoft Office Outlook.

Use

In society

Flaming

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.

In business

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.

Pros

• The problem of logistics

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. Email 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.

• The problem of synchronization

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.

Cons

Most business professionals today spend between 20% and 50% of their working time using e-mail^[9] : reading, ordering, sorting, ‘re-contextualizing’ fragmented information and of course writing emails. 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:

• Loss of Context: Information in context (as in a newspaper) is much easier and faster to understand than unsorted fragments. Communicating in context is faster and more efficient.
• Spam: E-mail is a push-only medium: control of who receives information lies primarily with the sender. This can lead to an overflow of unwanted or irrelevant information.
• Inconsistency: E-mail can duplicate information. This may be a problem when a team is collaboratively working on documents.

Despite these disadvantages, and despite the availability of other tools, e-mail-based communication is still the most widely used written medium in businesses.

Challenges

Spamming and computer viruses

The usefulness of e-mail is being threatened by three phenomena: spamming, phishing and e-mail worms.

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 tens or even hundreds of junk messages each day.

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 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. In the United States, U.S. Congress has also passed a law, the Can Spam Act of 2003, attempting to regulate such e-mail. Australia also has very strict spam laws restricting the sending of spam from an Australian ISP (http://www.aph.gov.au/library/pubs/bd/2003-04/04bd045.pdf), but its impact has been minimal since most spam comes from regimes that seem reluctant to regulate the sending of spam.

Privacy concerns

Main article: e-mail privacy

E-mail privacy, without some security precautions, can be compromised because:

• e-mail messages are generally not encrypted;
• e-mail messages have to go through intermediate computers before reaching their destination, meaning it is relatively easy for others to intercept and read messages;
• many Internet Service Providers (ISP) store copies of your e-mail messages on their mail servers before they are delivered. The backups of these can remain up to several months on their server, even if you delete them in your mailbox;
• the Received: headers and other information in the e-mail can often identify the sender, preventing anonymous communication.

There are cryptography applications that can serve as a remedy to one or more of the above. 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.

Additionally, many mail user agents do not protect logins and passwords, making them easy to intercept by an attacker. Encrypted authentication schemes such as SASL prevent this.

Finally, attached files share many of the same hazards as those found in peer-to-peer filesharing. Attached files may contain trojans or viruses.

Tracking of sent mail

E-mail traditionally provides no mechanism for tracking a sent message. The system(s) involved will generally make an effort to either deliver mail or return a failure notice ("bounce message"), but there is no guarantee that a message will actually be delivered, let alone read by the recipient. This is in contrast to the postal mail system, which offers registered mail or other forms of tracking and tracing.

To remedy this, mechanisms like Delivery Status Notifications (DSN) and return receipts were introduced.

US Government

The US Government has been involved in email 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 email 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 tarrif.^[10] Three years after initiating the service, USPS canceled E-COM and attempted to sell it off.^{[11] [12] [13] [14] [15] [16] [17]}

Early on in the history of the ARPANet, there were multiple email clients which had various, and at times, incompatible formats. For example, in the system Multics, the "@" sign meant "kill line" and anything after the "@" sign would be ignored. ^[18] The Department of Defense DARPA desired to have uniformity and interoperability for email and therefore funded efforts to drive towards unified interoperable standards. This led to David Crocker, John Vittal, Kenneth Pogran, Austin Henderson, 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 Jon Postel, 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 email systems at the time. This, in turn, lead to the release of David Crocker, RFC 822, Standard for the Format of ARPA Internet Text Messages (Aug. 13, 1982).^[19]

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. A part of the NSFNet AUP was that no commercial traffic would be permitted.^[20] In 1988, Vint Cerf arranged for an interconnection of MCI Mail with NSFNET on an experimental basis. The following year Compuserve email interconnected with NSFNET. Within a few years the commercial traffic restriction was removed from NSFNETs AUP, and NSFNET was privitized.

In the late 1990s, the Federal Trade Commission grew concerned with fraud transpiring in email, and initiated a series of procedures on SPAM, fraud, and phishing.^[21] In 2004, FTC jurisdiction over SPAM was codified into law in the form of the CAN SPAM Act.^[22] Several other US Federal Agencies have also exercised jurisdiction including the Department of Justice and the Secret Service.

See also

Enhancements

• BlackBerry
• E-mail encryption
• HTML e-mail
• Internet fax
• L-mail
• Push e-mail

E-mail social issues

• E-mail spoofing
• Netiquette
• Information overload
• Internet humor
• Internet slang
• E-mail spam
• Anti-spam techniques (e-mail)
• Computer virus
• E-card
• Usenet quoting
• E-mail art
• Reply All

Clients and servers

• E-mail client, Comparison of e-mail clients
• E-mail address
• E-mail authentication
• Internet mail standards
• Mail transfer agent
• Webmail
• E-mail hosting service
• Unicode and e-mail
• biff

Mailing list

• Electronic mailing list
• Mailing list archive
• Anonymous remailer
• Disposable e-mail address
• E-mail tracking
• E-mail encryption

Protocols

• SMTP
• X400

References

Notes

1. ^ "Email" is preferred by Google [1], Yahoo [2] and Apple [3]. Microsoft's use of the hyphenated spelling, "e-mail", is an exception to the computer industry's prevailing spelling.
2. ^ http://www.faqs.org/rfcs/rfc2821.html
3. ^ http://www.faqs.org/rfcs/rfc1939.html
4. ^ http://www.faqs.org/rfcs/rfc3501.html
5. ^ "CTSS, Compatible Time-Sharing System" (September 4, 2006), University of South Alabama, web: USA-CTSS.
6. ^ Tom Van Vleck, "The IBM 7094 and CTSS" (September 10, 2004), Multicians.org (Multics), web: Multicians-7094.
7. ^ http://www.multicians.org/thvv/mail-history.html
8. ^ http://openmap.bbn.com/~tomlinso/ray/firstemailframe.html
9. ^ Email Right to Privacy - Why Small Businesses Care. Anita Campbell (2007-06-19).
10. ^ In re Request for declaratory ruling and investigation by Graphnet Systems, Inc., concerning the proposed E-COM service, FCC Docket No. 79-6 (Sept 4, 1979)
11. ^ History of the United States Postal Service, USPS
12. ^ Hardy, Ian R; The Evolution of ARPANET Email; 1996-05-13; History Thesis; University of California at Berkeley
13. ^ James Bovard, The Law Dinosaur: The US Postal Service, CATO Policy Analysis (Feb. 1985)
14. ^ Jay Akkad, The History of Email
15. ^ Cybertelecom :: Email
16. ^ US Postal Service: Postal Activities and Laws Related to Electronic Commerce, GAO-00-188
17. ^ Implications of Electronic Mail and Message Systems for the U.S. Postal Service , Office of Technology Assessment, Congress of the United States, August 1982
18. ^ Jay Akkad, The History of Email
19. ^ Email History, How Email was Invented , Living Internet
20. ^ Cybertelecom :: Internet History
21. ^ Cybertelecom :: SPAM Reference
22. ^ Cybertelecom :: Can Spam Act

Bibliography

• Free On-line Dictionary of Computing
• Microsoft Manual of Style for Technical Publications Version 3.0

External links

• The History of Electronic Mail is a personal memoir by the implementer of one of the first e-mail systems
• IANA's list of standard header fieldsru-sib:Авессяzh-yue:電郵

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - e-mail, elektronisk post
v. tr. - sende e-mail til
abbr. - elektronisk post

Français (French)
n. - (Comput) courrier électronique
v. tr. - envoyer un message électronique/un e-mail à qn
abbr. - E-MAIL

Deutsch (German)
n. - elektronische Post
v. - elektronische Post versenden
abbr. - e-mail

Ελληνική (Greek)
n. - ηλεκτρονικό ταχυδρομείο
v. - στέλνω με ηλεκτρονικό ταχυδρομείο
abbr. - ηλεκτρονικό ταχυδρομείο

Italiano (Italian)
smalto, smaltare

Português (Portuguese)
n. - correio (m) eletrônico
v. - enviar mensagem de correio eletrônico
abbr. - e-mail (m)

Русский (Russian)
электронная почта, отправлять электронной почтой

Español (Spanish)
n. - correo electrónico
v. tr. - enviar por correo electrónico

Svenska (Swedish)
n. - e-post
v. - skicka e-post
abbr. - electronic mail

中文（简体） (Chinese (Simplified))
电子邮件, 写电子邮件

中文（繁體） (Chinese (Traditional))
n. - 電子郵件
v. tr. - 寫電子郵件
abbr. - 電子郵件

한국어 (Korean)
n. - 전자 우편
v. tr. - 전자 우편을 보내다
abbr. - electronic mail (전자 우편)

日本語 (Japanese)
n. - エナメル

עברית (Hebrew)
n. - ‮דואר אלקטרוני‬
v. tr. - ‮שלח דואר אלקטרוני‬
abbr. - ‮דואר אלקטרוני‬

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