Computer Mediated Communication (CMC)

Computer Mediated
Communication
Wikibook ITEC30011

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Contents
Articles
Computer-mediated communication 1
Email 4
Instant messaging 19
Social networking service 28
Opportunity cost 41
Acceptable use policy 43

References
Article Sources and Contributors 46
Image Sources, Licenses and Contributors 49

Article Licenses
License 50


Computer-mediated communication
Computer-mediated communication (CMC) is defined as any communicative transaction that occurs through the
use of two or more networked computers.[1] While the term has traditionally referred to those communications that
occur via computer-mediated formats (e.g., instant messages, e-mails, chat rooms), it has also been applied to other
forms of text-based interaction such as text messaging.[2] Research on CMC focuses largely on the social effects of
different computer-supported communication technologies. Many recent studies involve Internet-based social
networking supported by social software.

Scope of the field
Scholars from a variety of fields study phenomena that can be described under the umbrella term of CMC (see also
Internet studies). For example, many take a sociopsychological approach to CMC by examining how humans use
"computers" (or digital media) to manage interpersonal interaction, form impressions and form and maintain
relationships.[3] [4] These studies have often focused on the differences between online and offline interactions,
though contemporary research is moving towards the view that CMC should be studied as embedded in everyday life
.[5] Another branch of CMC research examines the use of paralinguistic features such as emoticons, pragmatic rules
such as turn-taking[6] and the sequential analysis and organization of talk,[7] [8] and the various sociolects, styles,
registers or sets of terminology specific to these environments (see Leet). The study of language in these contexts is
typically based on text-based forms of CMC, and is sometimes referred to as "computer-mediated discourse
analysis".[9]
The way humans communicate in professional, social, and educational settings varies widely, depending upon not
only the environment but also the method of communication in which the communication occurs, which in this case
is through computers or other information and computer technologies (ICTs). The study of communication to
achieve collaboration—common work products—is termed computer-supported collaboration and includes only
some of the concerns of other forms of CMC research.
Popular forms of CMC include e-mail, video, audio or text chat (text conferencing including "instant messaging"),
bulletin boards, list-servs and MMOs.[10] These settings are changing rapidly with the development of new
technologies. Weblogs (blogs) have also become popular, and the exchange of RSS data has better enabled users to
each "become their own publisher".

Characteristics
Communication occurring within a computer-mediated format has an effect on many different aspects of an
interaction. Some of these that have received attention in the scholarly literature include impression formation,
deception, group dynamics, disinhibition and especially relationship formation.
CMC is examined and compared to other communication media through a number of aspects thought to be universal
to all forms of communication, including (but not limited to) synchronicity, persistence or "recordability", and
anonymity. The association of these aspects with different forms of communication varies widely. For example,
instant messaging is intrinsically synchronous but not persistent, since one loses all the content when one closes the
dialog box unless one has a message log set up or has manually copy-pasted the conversation. E-mail and message
boards, on the other hand, are low in synchronicity since response time varies, but high in persistence since messages
sent and received are saved. Properties that separate CMC from other media also include transience, its multimodal
nature, and its relative lack of governing codes of conduct.[11] CMC is able to overcome physical and social
limitations of other forms of communication and therefore allow the interaction of people who are not physically
sharing the same space.


Anonymity and in part privacy and security depends more on the context and particular program being used or web
page being visited. However, most researchers in the field acknowledge the importance of considering the
psychological and social implications of these factors alongside the technical "limitations".

Types
CMC can be divided into synchronous and asynchronous modes. In synchronous communications all participants are
online at the same time (e.g. IRC), while asynchronous communications occurs with time constraints. (e.g e mail)

Language learning
CMC is widely discussed in language learning because CMC provides opportunities for language learners to practice
their language.[12] For example, Warschauer[13] conducted several case studies on using email or discussion boards
in different language classes. Warschauer[14] claimed that information and communications technology “bridge the
historic divide between speech … and writing”. Thus, considerable concern has arisen over the reading and writing
research in L2 due to the booming of Internet.

References
[1] McQuail, Denis. (2005). Mcquail's Mass Communication Theory. 5th ed. London: SAGE Publications.
[2] Thurlow, C., Lengel, L. & Tomic, A. (2004). Computer mediated communication: Social interaction and the internet. London: Sage.
[3] Walther, J. B. (1996). Computer-mediated communication: Impersonal, interpersonal, and hyperpersonal interaction. Communication
Research, 23, 3-43.
[4] Walther, J. B., & Burgoon, J. K. (1992). Relational communication in computer-mediated interaction. Human Communication Research, 19,
50-88.
[5] Haythornthwaite, C. and Wellman, B. (2002). The Internet in everyday life: An introduction. In B. Wellman and C. Haythornthwaite (Eds.),
The Internet in Everyday Life (pp. 3-41). Oxford: Blackwell.
[6] Garcia, A. C., & Jacobs, J. B. (1999). The eyes of the beholder: Understanding the turn-taking system in quasi-synchronous
computer-mediated communication. Research on Language & Social Interaction, 32, 337-367.
[7] Herring, S. (1999). Interactional coherence in CMC. Journal of Computer-Mediated Communication, 4(4). http:/ / jcmc. indiana. edu/ vol4/
issue4/ herring. html
[8] Markman, K. M. (2006). Computer-mediated conversation: The organization of talk in chat-based virtual team meetings. Dissertation
Abstracts International, 67 (12A), 4388. (UMI No. 3244348)
[9] Herring, S. C. (2004). Computer-mediated discourse analysis: An approach to researching online behavior. In: S. A. Barab, R. Kling, and J.
H. Gray (Eds.), Designing for Virtual Communities in the Service of Learning (pp. 338-376). New York: Cambridge University Press.
[10] Bishop, J. (2009). Enhancing the understanding of genres of web-based communities: The role of the ecological cognition framework.
International Journal of Web-Based Communities, 5(1), 4-17. Available online (http:/ / crocels. com/ index. php?q=node/ 6)
[11] McQuail, Denis. (2005). Mcquail's Mass Communication Theory. 5th ed. London: SAGE Publications.
[12] Abrams, Z. (2006). From Theory to Practice: Intracultural CMC in the L2 Classroom. book chapter, forthcoming in Ducate, Lara & Nike
Arnold (Eds.) Calling on CALL: From Theory and Research to New Directions in Foreign Language Teaching.
[13] Warschauer, M. (1998). Electronic literacies: Language, culture and power in online education. Mahwah, NJ: Lawrence Erlbaum Associates.
[14] Warschauer, M. (2006). Laptops and literacy: learning in the wireless classroom: Teachers College, Columbia University.

Further reading
Ahern, T.C., Peck, K., & Laycock, M. (1992). The effects of teacher discourse in computer-mediated discussion.
Journal of Educational Computing Research, 8(3), 291-309.
Angeli, C., Valanides, N., & Bonk, C.J. (2003). Communication in a web-based conferencing system: The quality of
computer-mediated interactions. British Journal of Educational Technology, 34(1), 31-43.
Bannan-Ritland, B. (2002). Computer-mediated communication, elearning, and interactivity: A review of the
research. Quarterly Review of Distance Education, 3(2), 161-180.
Christopher, M.M., Thomas, J.A., and Tallent-Runnels, M.K. (2004). Raising the Bar: Encouraging high level
thinking in online discussion forums. Roeper Review, 26(3), 166-171.


Cooper, M.M., & Selfe, C.L. (1990). Computer conferences and learning: Authority, resistance, and internally
persuasive discourse. College English, 52(8), 847-869.
Forman, E.A. (2000). Knowledge building in discourse communities. Human Development, 43(6), 364-368.
Gabriel, M.A. (2004). Learning together: Exploring group interactions online. Journal of Distance Education, 19(1),
54-72.
Gilbert, K.G., & Dabbagh, N. (2005). How to structure online discussions for meaningful discourse: a case study.
British Journal of Educational Technology, 36(1), 5-18.
Gunawardena, C.H., Nolla, A.C., Wilson, P.L., Lopez-Isias, Jr. et al. (2001). A cross-cultural study of group process
and development in online conferences. Distance Education, 22(1), 85-122.
Hara, N., Bonk, C.J., & Angeli, C. (2000). Content analysis of online discussion in an applied educational
psychology course. Instructional Science, 28, 115-152.
Hewitt, J. (2001). Beyond threaded discourse. International Journal of Educational Telecommunications, 7(3),
207-221.
Hewitt, J. (2003). How habitual online practices affect the development of asynchronous discussion threads. Journal
of Educational Computing Research, 28(1), 31-45.
Javela, S., Bonk, C.J., & Sirpalethti, S.L. (1999). A theoretical analysis of social interactions in computer-based
learning environments: Evidence for reciprocal understandings. Journal of Educational Computing Research, 21(3),
363-388.
Jones, G., & Schieffelin, B. (2009). Enquoting Voices, Accomplishing Talk: Uses of Be+Like in Instant Messaging.
Language & Communication, 29(1), 77-113.
Jones, G., & Schieffelin, B. (2009). Talking Text and Talking Back: "My BFF Jill" from Boob Tube to YouTube.
Journal of Computer-Mediated Communication, 14(4), 1050 - 1079.
Kalman, Y. M. and Rafaeli, S. (2007-05-23). Modulating Synchronicity in Computer-Mediated Communication.
Paper presented at the annual meeting of the International Communication Association, TBA, San Francisco, CA
Online <APPLICATION/PDF>. 2010-01-24 from http://www.allacademic.com/meta/p170694_index.html
Kirk, J.J., & Orr, R.L. (2003). A primer on the effective use of threaded discussion forums. ERIC document.
Lapadat, J.C. (2003). Teachers in an online seminar talking about talk: Classroom discourse and school change.
Language and Education, 17(1), 21-41.
Leinonen, P., Jarvela, S., & Lipponen, L. (2003). Individual students’ interpretations of their contribution to the
computer-mediated discussions. Journal of Interactive Learning Research, 14(1), 99-122.
Lin, L. (2008). An online learning model to facilitate learners’ rights to education. Journal of Asynchronous Learning
Networks (JALN), 12(1), pp. 127–143. [Special issue distributed by Sloan-C JALN in collaboration with five other
international journals: http://www.distanceandaccesstoeducation.org/]
Lin, L., Cranton, P. & Bridglall, B. (2005). Psychological type and asynchronous written dialogue in adult learning.
Teachers College Record, 107(8), 1788-1813.
MackNnight, C.B. (2000). Teaching critical thinking through online discussions. Educause Quarterly, 4, 38-41.
Poole, D.M. (2000). Student participation in a discussion-oriented online course: A case study. Journal of Research
on Computing in Education, 33(2), 162-176.
Schrire, S. (2003). A model for evaluating the process of learning in asynchronous computer conferencing. Journal
of Instructional Delivery Systems, 17(1), 6-12.
Vonderwell, S. (2002). An examination of asynchronous communication experiences and perspectives of students in
an online course: A case study. The Internet and Higher Education, 6, 77-90.


Wade, S.E., & Fauske, J.R. (2004). Dialogue online: Prospective teachers’ discourse strategies in computer-mediated
discussions. Reading Research Quarterly, 39(2), 134-160.
Wu, D., & Hiltz, S.R. (2004). Predicting learning from asynchronous online discussions. Journal of Asynchronous
Learning Networks, 8(2), 139-152.

Email
Electronic mail, commonly called email or e-mail, is a method of
exchanging digital messages from an author to one or more recipients.
Modern email operates across the Internet or other computer networks. Some
early email systems required that the author and the recipient both be online
at the same time, a la instant messaging. Today's email systems are based on
a store-and-forward model. Email servers accept, forward, deliver and store
messages. Neither the users nor their computers are required to be online
simultaneously; they need connect only briefly, typically to an email server,
for as long as it takes to send or receive messages.

An email message consists of three components, the message envelope, the The at sign, a part of every SMTP email
[1]
message header, and the message body. The message header contains control address

information, including, minimally, an originator's email address and one or
more recipient addresses. Usually descriptive information is also added, such as a subject header field and a message
submission date/time stamp.
Originally a text-only (7-bit ASCII and others) communications medium, email was extended to carry multi-media
content attachments, a process standardized in RFC 2045 through 2049. Collectively, these RFCs have come to be
called Multipurpose Internet Mail Extensions (MIME).
The history of modern, global Internet email services reaches back to the early ARPANET. Standards for encoding
email messages were proposed as early as 1973 (RFC 561). Conversion from ARPANET to the Internet in the early
1980s produced the core of the current services. An email sent in the early 1970s looks quite similar to a basic text
message sent on the Internet today.
Network-based email was initially exchanged on the ARPANET in extensions to the File Transfer Protocol (FTP),
but is now carried by the Simple Mail Transfer Protocol (SMTP), first published as Internet standard 10 (RFC 821)
in 1982. In the process of transporting email messages between systems, SMTP communicates delivery parameters
using a message envelope separate from the message (header and body) itself.

Spelling
There are several spelling options that occasionally prove cause for surprisingly vehement disagreement.[2] [3]
• email is the form required by IETF Requests for Comment and working groups[4] and increasingly by style
guides.[5] [6] [7] This spelling also appears in most dictionaries.[8] [9] [10] [11] [12] [13]
• e-mail is a form previously recommended by some prominent journalistic and technical style guides. According to
Corpus of Contemporary American English data, this form appears most frequently in edited, published American
English writing.[14]
• mail was the form used in the original RFC. The service is referred to as mail and a single piece of electronic mail
is called a message.[15] [16] [17]
• eMail, capitalizing only the letter M, was common among ARPANET users and the early developers of Unix,
CMS, AppleLink, eWorld, AOL, GEnie, and Hotmail.

Email 5

• EMail is a traditional form that has been used in RFCs for the "Author's Address",[16] [17] and is expressly
required "...for historical reasons...".[18]
• E-mail, capitalizing the initial letter E in the same way as A-bomb, H-bomb, X-ray, T-shirt, and similar
shortenings.[19]

Origin
Electronic mail predates the inception of the Internet, and was in fact a crucial tool in creating it.[20]
MIT first demonstrated the Compatible Time-Sharing System (CTSS) in 1961.[21] It allowed multiple users to log
into the IBM 7094[22] from remote dial-up terminals, and to store files online on disk. This new ability encouraged
users to share information in new ways. Email started in 1965 as a way for multiple users of a time-sharing
mainframe computer to communicate. Among the first systems to have such a facility were SDC's Q32 and MIT's
CTSS.

Host-based mail systems
The original email systems allowed communication only between users who logged into the same host or
"mainframe". This could be hundreds or even thousands of users within an organization. Examples include MIT's
1965 CTSS MAIL,[23] Larry Breed's 1972 APL Mailbox (which was used by the 1976 Carter/Mondale presidential
campaign),[24] [25] the original 1972 Unix mail program,[26] [27] IBM's 1981 PROFS, and Digital Equipment
Corporation's 1982 ALL-IN-1,.[28]

Homogeneous email networks and LAN-based mail systems
Many early peer-to-peer email networking only worked among computers running the same OS or program.
Examples include:
• By 1966 or earlier, it is possible that the SAGE system had a limited form of email
• 1978's uucp[29] and 1980's Usenet provided Unix-to-Unix copying of email, files, and shared fora over dialup
modems or leased lines
• BITNET in 1981 allowed IBM mainframes to communicate email over leased lines.
• FidoNet's 1984 application software for IBM PC's running DOS transferred email and shared bulletin board
postings by dialup modem
In the early 1980s, networked personal computers on LANs became increasingly important. Server-based systems
similar to the earlier mainframe systems were developed. Again these systems initially allowed communication only
between users logged into the same server infrastructure. Eventually these systems could also be linked between
different organizations, as long as they ran the same email system and proprietary protocol.
Examples include cc:Mail, Lantastic, WordPerfect Office, Microsoft Mail, Banyan VINES and Lotus Notes - with
various vendors supplying gateway software to link these incompatible systems.

Email 6

Attempts at interoperability
Early interoperability among independent systems included:
• ARPANET, the forerunner of today's Internet, defined the first protocols for dissimilar computers to exchange
email
• uucp implementations for non-Unix systems were used as an open "glue" between differing mail systems,
primarily over dialup telephones
• CSNet used dial-up telephone access to link additional sites to the ARPANET and then Internet
Later efforts at interoperability standardization included:
• Novell briefly championed the open MHS protocol but abandoned it after purchasing the non-MHS WordPerfect
Office (renamed Groupwise)
• The Coloured Book protocols on UK academic networks until 1992
• X.400 in the 1980s and early 1990s was promoted by major vendors and mandated for government use under
GOSIP but abandoned by all but a few — in favor of Internet SMTP by the mid-1990s.

From SNDMSG to MSG
In the early 1970s, Ray Tomlinson updated an existing utility called SNDMSG so that it could copy messages (as
files) over the network. Lawrence Roberts, the project manager for the ARPANET development, took the idea of
READMAIL, which dumped all "recent" messages onto the user's terminal, and wrote a program for TENEX in
TECO macros called RD which permitted accessing individual messages.[30] Barry Wessler then updated RD and
called it NRD.
Marty Yonke combined rewrote NRD to include reading, access to SNMSG for sending, and a help system, and
called the utility WRD which was later known as BANANARD. John Vittal then updated this version to include
message forwarding and an Answer command that automatically created a reply message with the correct
address(es). This was the first email "reply" command; the system was called MSG. With inclusion of these features,
MSG is considered to be the first integrated modern email program, from which many other applications have
descended.[30]

The rise of ARPANET mail
The ARPANET computer network made a large contribution to the development of email. There is one report that
indicates experimental inter-system email transfers began shortly after its creation in 1969.[23] Ray Tomlinson is
generally credited as having sent the first email across a network, initiating the use of the "@" sign to separate the
names of the user and the user's machine in 1971, when he sent a message from one Digital Equipment Corporation
DEC-10 computer to another DEC-10. The two machines were placed next to each other.[31] [32] Tomlinson's work
was quickly adopted across the ARPANET, which significantly increased the popularity of email. For many years,
email was the killer app of the ARPANET and then the Internet.
Most other networks had their own email protocols and address formats; as the influence of the ARPANET and later
the Internet grew, central sites often hosted email gateways that passed mail between the Internet and these other
networks. Internet email addressing is still complicated by the need to handle mail destined for these older networks.
Some well-known examples of these were UUCP (mostly Unix computers), BITNET (mostly IBM and VAX
mainframes at universities), FidoNet (personal computers), DECNET (various networks) and CSNET a forerunner of
NSFNet.
An example of an Internet email address that routed mail to a user at a UUCP host:

hubhost!middlehost!edgehost!user@uucpgateway.somedomain.example.com

Email 7

This was necessary because in early years UUCP computers did not maintain (or consult servers for) information
about the location of all hosts they exchanged mail with, but rather only knew how to communicate with a few
network neighbors; email messages (and other data such as Usenet News) were passed along in a chain among hosts
who had explicitly agreed to share data with each other.

Operation overview
The diagram to the right shows a typical sequence of events[33] that takes place when Alice composes a message
using her mail user agent (MUA). She enters the email address of her correspondent, and hits the "send" button.

1. Her MUA formats the message in email format and uses the Submission Protocol (a profile of the Simple Mail
Transfer Protocol (SMTP), see RFC 4409) to send the message to the local mail submission agent (MSA), in this
case smtp.a.org, run by Alice's internet service provider (ISP).
2. The MSA looks at the destination address provided in the SMTP protocol (not from the message header), in this
case bob@b.org. An Internet email address is a string of the form localpart@exampledomain. 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 or a fully qualified domain name. The MSA resolves a domain name to determine the fully
qualified domain name of the mail exchange server in the Domain Name System (DNS).
3. The DNS server for the b.org domain, ns.b.org, responds with any MX records listing the mail exchange
servers for that domain, in this case mx.b.org, a message transfer agent (MTA) server run by Bob's ISP.
4. smtp.a.org sends the message to mx.b.org using SMTP.
This server may need to forward the message to other MTAs before the message reaches the final message delivery
agent (MDA).
1. The MDA delivers it to the mailbox of the user bob.
2. Bob presses the "get mail" button in his MUA, which picks up the message using either the Post Office Protocol
(POP3) or the Internet Message Access Protocol (IMAP4).
That sequence of events applies to the majority of email users. However, there are many alternative possibilities and
complications to the email system:
• Alice or Bob may use a client connected to a corporate email system, such as IBM Lotus Notes or Microsoft
Exchange. These systems often have their own internal email format and their clients typically communicate with
the email server using a vendor-specific, proprietary protocol. The server sends or receives email via the Internet

Email 8

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 email 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 email in many ways, for example 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.
• Email messages are not secure if email encryption is not used correctly.
Many MTAs used to accept messages for any recipient on the Internet and do their best to deliver them. Such MTAs
are called open mail relays. This was very 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 closer to the destination.
The relay stood a better chance of delivering the message at a later time. However, this mechanism proved to be
exploitable by people sending unsolicited bulk email and as a consequence very few modern MTAs are open mail
relays, and many MTAs don't accept messages from open mail relays because such messages are very likely to be
spam.

Message format
The Internet email message format is defined in RFC 5322, with multi-media content attachments being defined in
RFC 2045 through RFC 2049, collectively called Multipurpose Internet Mail Extensions or MIME. Prior to the
introduction of RFC 2822 in 2001, the format described by RFC 822 was the standard for Internet email for nearly
20 years. RFC 822 was published in 1982 and based on the earlier RFC 733 for the ARPANET (see).[34]
Internet email messages consist of two major sections:
• Header — Structured into fields such as From, To, CC, Subject, Date, and other information about the email.
• Body — The basic content, as unstructured text; sometimes containing a signature block at the end. This is
exactly the same as the body of a regular letter.
The header is separated from the body by a blank line.

Message header
Each message has exactly one header, which is structured into fields. Each field has a name and a value. RFC 5322
specifies the precise syntax.
Informally, each line of text in the header that begins with a printable character begins a separate field. The field
name starts in the first character of the line and ends before the separator character ":". The separator is then
followed by the field value (the "body" of the field). The value is continued onto subsequent lines if those lines 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.

Email 9

Header fields
The message header must include at least the following fields[35] :
• From: The email address, and optionally the name of the author(s). In many email clients not changeable except
through changing account settings.
• Date: The local time and date when the message was written. Like the From: field, many email clients fill this in
automatically when sending. The recipient's client may then display the time in the format and time zone local to
him/her.
The message header should include at least the following fields[36] :
• Message-ID: Also an automatically generated field; used to prevent multiple delivery and for reference in
In-Reply-To: (see below).
• In-Reply-To: Message-ID of the message that this is a reply to. Used to link related messages together. This field
only applies for reply messages.
RFC 3864 describes registration procedures for message header fields at the IANA; it provides for permanent [37]
and provisional [38] message header field names, including also fields defined for MIME, netnews, and http, and
referencing relevant RFCs. Common header fields for email include:
• To: The email address(es), and optionally name(s) of the message's recipient(s). Indicates primary recipients
(multiple allowed), for secondary recipients see Cc: and Bcc: below.
• Subject: A brief summary of the topic of the message. Certain abbreviations are commonly used in the subject,
including "RE:" and "FW:".
• Bcc: Blind Carbon Copy; addresses added to the SMTP delivery list but not (usually) listed in the message data,
remaining invisible to other recipients.
• Cc: Carbon copy; Many email clients will mark email in your inbox differently depending on whether you are in
the To: or Cc: list.
• Content-Type: Information about how the message is to be displayed, usually a MIME type.
• Precedence: commonly with values "bulk", "junk", or "list"; used to indicate that automated "vacation" or "out of
office" responses should not be returned for this mail, e.g. to prevent vacation notices from being sent to all other
subscribers of a mailinglist. Sendmail uses this header to affect prioritization of queued email, with "Precedence:
special-delivery" messages delivered sooner. With modern high-bandwidth networks delivery priority is less of an
issue than it once was. Microsoft Exchange respects a fine-grained automatic response suppression mechanism,
the X-Auto-Response-Suppress header.[39]
• Received: Tracking information generated by mail servers that have previously handled a message, in reverse
order (last handler first).
• References: Message-ID of the message that this is a reply to, and the message-id of the message the previous was
reply a reply to, etc.
• Reply-To: Address that should be used to reply to the message.
• Sender: Address of the actual sender acting on behalf of the author listed in the From: field (secretary, list
manager, etc.).
Note that the To: field is not necessarily related to the addresses to which the message is delivered. The actual
delivery list is supplied separately to the transport protocol, SMTP, which may or may not originally have been
extracted from the header content. The "To:" field is similar to the addressing 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 email message. One reason is that 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 email, which is much harder to fake, but such
signatures require extra programming and often external programs to verify. Some ISPs do not relay email claiming
to come from a domain not hosted by them, but very few (if any) check to make sure that the person or even email
address named in the "From:" field is the one associated with the connection. Some ISPs apply email authentication

Email 10

systems to email being sent through their MTA to allow other MTAs to detect forged spam that might appear to
come from them.
Recently the IETF EAI working group has defined some experimental extensions to allow Unicode characters to be
used within the header. In particular, this allows email addresses to use non-ASCII characters. Such characters must
only be used by servers that support these extensions.

Message body

Content encoding
Email was originally designed for 7-bit ASCII.[40] Much email software is 8-bit clean but must assume it will
communicate 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 and BINARY extensions
were introduced to allow transmission of mail without the need for these encodings, but many mail transport agents
still do not support them fully. In some countries, several encoding schemes coexist; as the result, by default, the
message in a non-Latin alphabet language appears in non-readable form (the only exception is coincidence, when the
sender and receiver use the same encoding scheme). Therefore, for international character sets, Unicode is growing
in popularity.

Plain text and HTML
Most modern graphic email clients allow the use of either plain text or HTML for the message body at the option of
the user. HTML email messages often include an automatically generated plain text copy as well, for compatibility
reasons.
Advantages of HTML include the ability to include in-line 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.
Disadvantages include the increased size of the email, privacy concerns about web bugs, abuse of HTML email as a
vector for phishing attacks and the spread of malicious software.[41]
Some web based Mailing lists recommend that all posts be made in plain-text, with 72 or 80 characters per line[42]
[43]
for all the above reasons, but also because they have a significant number of readers using text-based email
clients such as Mutt.
Some Microsoft email clients allow rich formatting using RTF, but unless the recipient is guaranteed to have a
compatible email client this should be avoided.[44]
In order to ensure that HTML sent in an email is rendered properly by the recipient's client software, an additional
header must be specified when sending: "Content-type: text/html". Most email programs send this header
automatically.

Servers and client applications
Messages are exchanged between hosts using the Simple Mail Transfer Protocol with software programs called mail
transfer agents. Users can retrieve their messages from servers using standard protocols such as POP or IMAP, or, as
is more likely in a large corporate environment, with a proprietary protocol specific to Novell Groupwise, Lotus
Notes or Microsoft Exchange Servers. Webmail interfaces allow users to access their mail with any standard web
browser, from any computer, rather than relying on an email client.
Mail can be stored on the client, on the server side, or in both places. Standard formats for mailboxes include Maildir
and mbox. Several prominent email clients use their own proprietary format and require conversion software to
transfer email between them.

Email 11

Accepting a message obliges an MTA to deliver it,[45] and when a message cannot be delivered, that MTA must send
a bounce message back to the sender, indicating the problem.

Filename extensions
Upon reception of email messages, email client applications save message in operating system files in the
file-system. Some clients save individual messages as separate files, while others use various database formats, often
proprietary, for collective storage. A historical standard of storage is the mbox format. The specific format used is
often indicated by special filename extensions:
eml
Used by many email clients including Microsoft Outlook Express, Windows Mail and Mozilla
Thunderbird.[46] The files are plain text in MIME format, containing the email header as well as the message
contents and attachments in one or more of several formats.
emlx
Used by Apple Mail.
msg
Used by Microsoft Office Outlook and OfficeLogic Groupware.
mbx
Used by Opera Mail, KMail, and Apple Mail based on the mbox format.
Some applications (like Apple Mail) leave attachments encoded in messages for searching while also saving separate
copies of the attachments. Others separate attachments from messages and save them in a specific directory.

URI scheme mailto:
The URI scheme, as registered with the IANA, defines the mailto: scheme for SMTP email addresses. Though
its use is not strictly defined, URLs of this form are intended to be used to open the new message window of the
user's mail client when the URL is activated, with the address as defined by the URL in the To: field.[47]

Use

In society
There are numerous ways in which people have changed the way they communicate in the last 50 years; email is
certainly one of them. Traditionally, social interaction in the local community was the basis for communication –
face to face. Yet, today face-to-face meetings are no longer the primary way to communicate as one can use a
landline telephone, mobile phones, fax services, or any number of the computer mediated communications such as
email.

Flaming
Flaming occurs when a person sends a message with angry or antagonistic content. Flaming is assumed to be more
common today because of the ease and impersonality of email 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. Flaming is generally looked down upon by Internet
communities as it is considered rude and non-productive.

Email 12

Email bankruptcy
Also known as "email fatigue", email bankruptcy is when a user ignores a large number of email 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. Harvard University law professor
Lawrence Lessig is credited with coining this term, but he may only have popularized it.[48]

In business
Email was widely accepted by the business community as the first broad electronic communication medium and was
the first ‘e-revolution’ in business communication. Email is very simple to understand and like postal mail, email
solves two basic problems of communication: logistics and synchronization (see below).
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 upon communications between people who are not
physically in the same building, area or even country; setting up and attending an in-person meeting, telephone
call, or conference call can be inconvenient, time-consuming, and costly. Email provides a way to exchange
information between two or more people with no set-up costs and that is generally far less expensive than
physical meetings or phone calls.
• The problem of synchronisation: With real time communication by meetings or phone calls, participants have to
work on the same schedule, and each participant must spend the same amount of time in the meeting or call.
Email allows asynchrony: each participant may control their schedule independently.

Cons
Most business workers today spend from one to two hours of their working day on email: reading, ordering, sorting,
‘re-contextualizing’ fragmented information, and writing email.[49] The use of email is increasing due to increasing
levels of globalisation—labour division and outsourcing amongst other things. Email can lead to some well-known
problems:
• Loss of context: which means that the context is lost forever; there is no way to get the text back. Information in
context (as in a newspaper) is much easier and faster to understand than unedited and sometimes unrelated
fragments of information. Communicating in context can only be achieved when both parties have a full
understanding of the context and issue in question.
• Information overload: Email is a push technology—the sender controls who receives the information. Convenient
availability of mailing lists and use of "copy all" can lead to people receiving unwanted or irrelevant information
of no use to them.
• Inconsistency: Email can duplicate information. This can be a problem when a large team is working on
documents and information while not in constant contact with the other members of their team.
• Liability. Statements made in an email can be deemed legally binding and be used against a party in a Court of
law.[50]
Despite these disadvantages, email has become the most widely used medium of communication within the business
world. In fact, a 2010 study on workplace communication [51], found that 83% of U.S. knowledge workers felt that
email was critical to their success and productivity at work.[52]

Email 13

Problems

Attachment size limitation
Email messages may have one or more attachments. Attachments serve the purpose of delivering binary or text files
of unspecified size. In principle there is no technical intrinsic restriction in the SMTP protocol limiting the size or
number of attachments. In practice, however, email service providers implement various limitations on the
permissible size of files or the size of an entire message.
Furthermore, due to technical reasons, often a small attachment can increase in size when sent,[53] which can be
confusing to senders when trying to assess whether they can or cannot send a file by email, and this can result in
their message being rejected.
As larger and larger file sizes are being created and traded, many users are either forced to upload and download
their files using an FTP server, or more popularly, use online file sharing facilities or services, usually over
web-friendly HTTP, in order to send and receive them.

Information overload
A December 2007 New York Times blog post described information overload as "a $650 Billion Drag on the
Economy",[54] 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 start-ups
focused on e-mail really eliminates the problem of e-mail overload because none helps us prepare replies".[55]
GigaOm posted a similar article in September 2010, highlighting research [56] that found 57% of knowledge workers
were overwhelmed by the volume of email they received.[52]
Technology investors reflect similar concerns.[57]

Spamming and computer viruses
The usefulness of email is being threatened by four phenomena: email bombardment, spamming, phishing, and email
worms.
Spamming is unsolicited commercial (or bulk) email. Because of the very low cost of sending email, spammers can
send hundreds of millions of email 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.[58] [59]
Email worms use email as a way of replicating themselves into vulnerable computers. Although the first email 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 email, which
reduces the usefulness of email 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 email. Australia also has very strict spam laws
restricting the sending of spam from an Australian ISP,[60] but its impact has been minimal since most spam comes
from regimes that seem reluctant to regulate the sending of spam.

Email 14

Email spoofing
Email spoofing occurs when the header information of an email is altered to make the message appear to come from
a known or trusted source. It is often used as a ruse to collect personal information.

Email bombing
Email bombing is the intentional sending of large volumes of messages to a target address. The overloading of the
target email address can render it unusable and can even cause the mail server to crash.

Privacy concerns
Today it can be important to distinguish between Internet and internal email systems. Internet email may travel and
be stored on networks and computers without the sender's or the recipient's control. During the transit time it is
possible that third parties read or even modify the content. Internal mail systems, in which the information never
leaves the organizational network, may be more secure, although information technology personnel and others
whose function may involve monitoring or managing may be accessing the email of other employees.
Email privacy, without some security precautions, can be compromised because:
• email messages are generally not encrypted.
• email 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 email messages on their mail servers before they are
delivered. The backups of these can remain for up to several months on their server, despite deletion from the
mailbox.
• the "Received:"-fields and other information in the email 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, SMEmail,[61] 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
The original SMTP mail service provides limited mechanisms for tracking a transmitted 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 complete Message
Tracking mechanism was also defined, but it never gained traction; see RFCs 3885 through 3888.)
Many ISPs now deliberately disable non-delivery reports (NDRs) and delivery receipts due to the activities of
spammers:
• Delivery Reports can be used to verify whether an address exists and so is available to be spammed
• If the spammer uses a forged sender email address (E-mail spoofing), then the innocent email address that was
used can be flooded with NDRs from the many invalid email addresses the spammer may have attempted to mail.

Email 15

These NDRs then constitute spam from the ISP to the innocent user
There are a number of systems that allow the sender to see if messages have been opened.[62] [63] [64] The receiver
could also let the sender know that the emails have been opened through an "Okay" button. A check sign can appear
in the sender's screen when the receiver's "Okay" button is pressed.

US Government
The US Government has been involved in email in several different ways.
Starting in 1977, the US Postal Service (USPS) recognized that 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 were transmitted to a post office, printed out, and delivered as hard
copy. 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. Both the Postal Regulatory 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.[65] Three years after initiating the service,
USPS canceled E-COM and attempted to sell it off.[66] [67] [68] [69] [70] [71]
The early ARPANET dealt with multiple email clients that had various, and at times incompatible, formats. For
example, in the system Multics, the "@" sign meant "kill line" and anything after the "@" sign was ignored.[69] The
Department of Defense DARPA desired to have uniformity and interoperability for email and therefore funded
efforts to drive towards unified inter-operable standards. This led to David Crocker, John Vittal, Kenneth Pogran,
and Austin Henderson publishing RFC 733, "Standard for the Format of ARPA Network Text Message" (November
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 email systems at the time. This, in
turn, lead to the release of David Crocker's RFC 822, "Standard for the Format of ARPA Internet Text Messages"
(August 13, 1982).[72]
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 forbade commercial
traffic.[73] 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 privatised.
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.[74] In 2004, FTC jurisdiction over spam was codified into law in
the form of the CAN SPAM Act.[75] Several other US Federal Agencies have also exercised jurisdiction including
the Department of Justice and the Secret Service.

Email 16

References
[1] Klensin, J (October 2008). "RFC 5321 — Simple Mail Transfer Protocol" (http:/ / tools. ietf. org/ html/ rfc5321#section-2. 3. 11). Network
Working Group. . Retrieved 2010-02-27.
[2] Long, Tony (23 October 2000). A Matter of (Wired News) Style (http:/ / www. nettime. org/ Lists-Archives/ nettime-bold-0010/ msg00471.
html). Wired magazine. .
[3] Readers on (Wired News) Style (http:/ / www. wired. com/ culture/ lifestyle/ news/ 2000/ 10/ 39651). Wired magazine. 24 October 2000. .
[4] "RFC Editor Terms List" (http:/ / www. rfc-editor. org/ rfc-style-guide/ terms-online-03. txt). IETF. .
[5] Yahoo style guide (http:/ / styleguide. yahoo. com/ word-list/ e)
[6] AP Stylebook editors share big changes (http:/ / www. aces2011. org/ sessions/ 18/ the-ap-stylebook-editors-visit-aces-2011/ ) from the
American Copy Editors Society
[7] Gerri Berendzen; Daniel Hunt. "AP changes e-mail to email" (http:/ / www. aces2011. org/ sessions/ 18/
the-ap-stylebook-editors-visit-aces-2011/ ). 15th National Conference of the American Copy Editors Society (2011, Phoenix). ACES. .
Retrieved 23 March 2011.
[8] AskOxford Language Query team. "What is the correct way to spell 'e' words such as 'email', 'ecommerce', 'egovernment'?" (http:/ / www.
askoxford. com/ asktheexperts/ faq/ aboutspelling/ email). FAQ. Oxford University Press. . Retrieved 4 September 2009. "We recommend
email, as this is now by far the most common form"
[9] Reference.com (http:/ / dictionary. reference. com/ browse/ email)
[10] Random House Unabridged Dictionary, 2006
[11] The American Heritage Dictionary of the English Language, Fourth Edition
[12] Princeton University WordNet 3.0
[13] The American Heritage Science Dictionary, 2002
[14] ""Email" or "e-mail"" (http:/ / english. stackexchange. com/ questions/ 1925/ email-or-e-mail). English Language & Usage — Stack
Exchange. August 25, 2010. . Retrieved September 26, 2010.
[15] RFC 821 (rfc821) - Simple Mail Transfer Protocol (http:/ / www. faqs. org/ rfcs/ rfc821. html)
[16] RFC 1939 (rfc1939) - Post Office Protocol - Version 3 (http:/ / www. faqs. org/ rfcs/ rfc1939. html)
[17] RFC 3501 (rfc3501) - Internet Message Access Protocol - version 4rev1 (http:/ / www. faqs. org/ rfcs/ rfc3501. html)
[18] "RFC Style Guide", Table of decisions on consistent usage in RFC (http:/ / www. rfc-editor. org/ rfc-style-guide/ terms-online-03. txt)
[19] Excerpt from the FAQ list of the Usenet newsgroup alt.usage.english (http:/ / alt-usage-english. org/ excerpts/ fxhowdoy. html)
[20] See (Partridge 2008) for early history of email, from origins through 1991.
[21] "CTSS, Compatible Time-Sharing System" (September 4, 2006), University of South Alabama, USA-CTSS (http:/ / www. cis. usouthal.
edu/ faculty/ daigle/ project1/ ctss. htm).
[22] Tom Van Vleck, "The IBM 7094 and CTSS" (September 10, 2004), Multicians.org (Multics), web: Multicians-7094 (http:/ / www.
multicians. org/ thvv/ 7094. html).
[23] Tom Van Vleck's memoir of The History of Electronic Mail (http:/ / www. multicians. org/ thvv/ mail-history. html)
[24] APL Quotations and Anecdotes (http:/ / www. jsoftware. com/ papers/ APLQA. htm), including Leslie Goldsmith's story of the Mailbox
[25] History of the Internet, including Carter/Mondale use of email (http:/ / www. actewagl. com. au/ Education/ communications/ Internet/
historyOfTheInternet/ InternetOnItsInfancy. aspx)
[26] Version 3 Unix mail(1) manual page from 10/25/1972 (http:/ / minnie. tuhs. org/ cgi-bin/ utree. pl?file=V3/ man/ man1/ mail. 1)
[27] Version 6 Unix mail(1) manual page from 2/21/1975 (http:/ / minnie. tuhs. org/ cgi-bin/ utree. pl?file=V6/ usr/ man/ man1/ mail. 1)
[28] Gordon Bell's timeline of Digital Equipment Corporation (https:/ / research. microsoft. com/ en-us/ um/ people/ gbell/ Digital/ timeline/
1982. htm)
[29] Version 7 Unix manual: "UUCP Implementation Description" by D. A. Nowitz, and "A Dial-Up Network of UNIX Systems" by D. A.
Nowitz and M. E. Lesk (http:/ / cm. bell-labs. com/ 7thEdMan/ vol2/ uucp. bun)
[30] Email History (http:/ / www. livinginternet. com/ e/ ei. htm)
[31] The First Email (http:/ / openmap. bbn. com/ ~tomlinso/ ray/ firstemailframe. html)
[32] Wave New World,Time Magazine, October 19, 2009, p.48
[33] How E-mail Works (http:/ / www. webcastr. com/ videos/ informational/ how-email-works. html). [internet video]. howstuffworks.com.
2008. .
[34] Simpson, Ken (October 3, 2008). "An update to the email standards" (http:/ / blog. mailchannels. com/ 2008/ 10/ update-to-email-standards.
html). Mail Channels Blog Entry. .
[35] RFC 5322, 3.6. Field Definitions (http:/ / tools. ietf. org/ html/ rfc5322#section-3. 6)
[36] RFC 5322, 3.6.4. Identification Fields (http:/ / tools. ietf. org/ html/ rfc5322#section-3. 6. 4)
[37] http:/ / www. iana. org/ assignments/ message-headers/ perm-headers. html
[38] http:/ / www. iana. org/ assignments/ message-headers/ prov-headers. html
[39] Microsoft, Auto Response Suppress, 2010, microsoft reference (http:/ / msdn. microsoft. com/ en-us/ library/ ee219609(v=EXCHG. 80).
aspx), 2010 Sep 22
[40] Craig Hunt (2002). TCP/IP Network Administration. O'Reilly Media. pp. 70. ISBN 978-0596002978.
[41] "Email policies that prevent viruses" (http:/ / advosys. ca/ papers/ mail-policies. html). .

Email 17

[42] "When posting to a RootsWeb mailing list..." (http:/ / helpdesk. rootsweb. com/ listadmins/ plaintext. html)
[43] "...Plain text, 72 characters per line..." (http:/ / www. openbsd. org/ mail. html)
[44] How to Prevent the Winmail.dat File from Being Sent to Internet Users (http:/ / support. microsoft. com/ kb/ 138053)
[45] In practice, some accepted messages may nowadays not be delivered to the recipient's InBox, but instead to a Spam or Junk folder which,
especially in a corporate environment, may be inaccessible to the recipient
[46] "File Extension .EML Details" (http:/ / filext. com/ file-extension/ EML). FILExt - The File Extension Source. . Retrieved 2009-09-26.
[47] RFC 2368 section 3 : by Paul Hoffman in 1998 discusses operation of the "mailto" URL.
[48] Barrett, Grant (December 23, 2007). "All We Are Saying." (http:/ / www. nytimes. com/ 2007/ 12/ 23/ weekinreview/ 23buzzwords.
html?ref=weekinreview). New York Times. . Retrieved 2007-12-24.
[49] "Email Right to Privacy - Why Small Businesses Care" (http:/ / www. smallbiztrends. com/ 2007/ 06/
email-has-right-to-privacy-why-small-businesses-care. html). Anita Campbell. 2007-06-19. .
[50] C. J. Hughes (February 17, 2011). "E-Mail May Be Binding, State Court Rules" (http:/ / www. nytimes. com/ 2011/ 02/ 20/ realestate/
20posting. html). New York Times. . Retrieved 2011-02-20.
[51] http:/ / www. plantronics. com/ north_america/ en_US/ howwework/
[52] By Om Malik, GigaOm. “ Is Email a Curse or a Boon? (http:/ / gigaom. com/ collaboration/ is-email-a-curse-or-a-boon/ )” September 22,
2010. Retrieved October 11, 2010.
[53] "Exchange 2007: Attachment Size Increase,..." (http:/ / technet. microsoft. com/ en-us/ magazine/ 2009. 01. exchangeqa. aspx?pr=blog).
TechNet Magazine, Microsoft.com US. 2010-03-25. .
[54] Lohr, Steve (2007-12-20). "Is Information Overload a $650 Billion Drag on the Economy?" (http:/ / bits. blogs. nytimes. com/ 2007/ 12/ 20/
is-information-overload-a-650-billion-drag-on-the-economy). New York Times. . Retrieved May 1, 2010.
[55] Stross, Randall (2008-04-20). "Struggling to Evade the E-Mail Tsunami" (http:/ / www. nytimes. com/ 2008/ 04/ 20/ technology/ 20digi.
html?_r=2& oref=slogin& oref=slogin). New York Times. . Retrieved May 1, 2010.
[56] http:/ / gigaom. com/ collaboration/ is-email-a-curse-or-a-boon/
[57] "Did Darwin Skip Over Email?" (http:/ / www. foundrygroup. com/ blog/ archives/ 2008/ 04/ did-darwin-skip-over-email. php). Foundry
Group. 2008-04-28. .
[58] Rich Kawanagh. The top ten email spam list of 2005. ITVibe news, 2006, january 02, ITvibe.com (http:/ / itvibe. com/ news/ 3837/ )
[59] How Microsoft is losing the war on spam Salon.com (http:/ / dir. salon. com/ story/ tech/ feature/ 2005/ 01/ 19/ microsoft_spam/ index.
html)
[60] Spam Bill 2003 ( PDF (http:/ / www. aph. gov. au/ library/ pubs/ bd/ 2003-04/ 04bd045. pdf))
[61] M. Toorani, SMEmail - A New Protocol for the Secure E-mail in Mobile Environments (http:/ / ieeexplore. ieee. org/ xpl/ freeabs_all.
jsp?arnumber=4783292), Proceedings of the Australian Telecommunications Networks and Applications Conference (ATNAC'08), pp.39-44,
Adelaide, Australia, December 2008. (arXiv:1002.3176)
[62] About.com (http:/ / email. about. com/ od/ emailbehindthescenes/ a/ html_return_rcp. htm)
[63] Webdevelopersnotes.com (http:/ / www. webdevelopersnotes. com/ tips/ yahoo/ notification-when-yahoo-email-is-opened. php)
[64] Microsoft.com (http:/ / support. microsoft. com/ kb/ 222163)
[65] In re Request for declaratory ruling and investigation by Graphnet Systems, Inc., concerning the proposed E-COM service, FCC Docket No.
79-6 (September 4, 1979)
[66] History of the United States Postal Service, USPS (http:/ / www. usps. com/ history/ history/ his1. htm)
[67] Hardy, Ian R; The Evolution of ARPANET Email (http:/ / www. archive. org/ web/ */ http:/ www. ifla. org/ documents/ internet/ hari1. txt);
1996-05-13; History Thesis Paper; University of California at Berkeley
[68] James Bovard, The Law Dinosaur: The US Postal Service, CATO Policy Analysis (February 1985)
[69] Jay Akkad, The History of Email (http:/ / www. cs. ucsb. edu/ ~almeroth/ classes/ F04. 176A/ homework1_good_papers/ jay-akkad. html)
[70] US Postal Service: Postal Activities and Laws Related to Electronic Commerce, GAO-00-188 (http:/ / www. gao. gov/ archive/ 2000/
gg00188. pdf)
[71] Implications of Electronic Mail and Message Systems for the U.S. Postal Service , Office of Technology Assessment, Congress of the
United States, August 1982 (http:/ / govinfo. library. unt. edu/ ota/ Ota_4/ DATA/ 1982/ 8214. PDF)
[72] Email History, How Email was Invented, Living Internet (http:/ / www. livinginternet. com/ e/ ei. htm)
[73] Cybertelecom : Internet History (http:/ / www. cybertelecom. org/ notes/ internet_history80s. htm)
[74] Cybertelecom : SPAM Reference (http:/ / www. cybertelecom. org/ spam/ Spamref. htm)
[75] Cybertelecom : Can Spam Act (http:/ / www. cybertelecom. org/ spam/ canspam. htm)

Email 18

Further reading
• Cemil Betanov, Introduction to X.400, Artech House, ISBN 0-89006-597-7.
• Lawrence Hughes, Internet e-mail Protocols, Standards and Implementation, Artech House Publishers, ISBN
0-89006-939-5.
• Kevin Johnson, Internet Email Protocols: A Developer's Guide, Addison-Wesley Professional, ISBN
0-201-43288-9.
• Pete Loshin, Essential Email Standards: RFCs and Protocols Made Practical, John Wiley & Sons, ISBN
0-471-34597-0.
• Partridge, Craig (April–June 2008). "The Technical Development of Internet Email" (http://www.ir.bbn.com/
~craig/email.pdf) (PDF). IEEE Annals of the History of Computing (Berlin: IEEE Computer Society) 30 (2).
ISSN 1934-1547
• Sara Radicati, Electronic Mail: An Introduction to the X.400 Message Handling Standards, Mcgraw-Hill, ISBN
0-07-051104-7.
• John Rhoton, Programmer's Guide to Internet Mail: SMTP, POP, IMAP, and LDAP, Elsevier, ISBN
1-55558-212-5.
• John Rhoton, X.400 and SMTP: Battle of the E-mail Protocols, Elsevier, ISBN 1-55558-165-X.
• David Wood, Programming Internet Mail, O'Reilly, ISBN 1-56592-479-7.

External links
• E-mail (http://www.dmoz.org/Computers/Internet/E-mail//) at the Open Directory Project
• IANA's list of standard header fields (http://www.iana.org/assignments/message-headers/perm-headers.html)
• The History of Electronic Mail (http://www.multicians.org/thvv/mail-history.html) is a personal memoir by
the implementer of an early email system


Instant messaging
Instant messaging (IM) is a form of real-time direct text-based
communication between two or more people using personal computers or
other devices, along with shared clients. The user's text is conveyed over
a network, such as the Internet. More advanced instant messaging
software clients also allow enhanced modes of communication, such as
live voice or video calling.

Definition
IM falls under the umbrella term online chat, as it is a real-time
text-based networked communication system, but is distinct in that it is
based on clients that facilitate connections between specified known users
(often using "Buddy List", "Friend List" or "Contact List"), whereas
online 'chat' also includes web-based applications that allow
communication between (often anonymous) users in a multi-user
environment.

Overview
Instant messaging (IM) is a collection of technologies used for real-time
text-based communication between two or more participants over the
Internet, or other types of networks. Of importance is that online chat and
instant messaging differs from other technologies such as e-mail due to
Pidgin 2.0 running under GNOME
the perceived synchronicity of the communications by the users –chat
happens in real-time. Some systems permit messages to be sent to people
not currently 'logged on' (offline messages), thus removing some of the differences between IM and e-mail (often
done by sending the message to the associated e-mail account).

IM allows effective and efficient communication, allowing immediate receipt of acknowledgment or reply. In many
cases instant messaging includes additional features which can make it even more popular. For example, users can
see each other by using webcams, or talk directly for free over the Internet using a microphone and headphones or
loudspeakers. Many client programs allow file transfers as well, although they are typically limited in the
permissible file-size.
It is typically possible to save a text conversation for later reference. Instant messages are often logged in a local
message history, making it similar to the persistent nature of e-mails.


History
Instant messaging predates the Internet,
first appearing on multi-user operating
systems like CTSS and Multics[1] in the
mid-1960s. Initially, some of these systems
were used as notification systems for
services like printing, but quickly were used
to facilitate communication with other users
logged in to the same machine. As networks
developed, the protocols spread with the
networks. Some of these used a peer-to-peer
protocol (e.g. talk, ntalk and ytalk), while
others required peers to connect to a server
(see talker and IRC). During the Bulletin
board system (BBS) phenomenon that In early instant messaging programs each character appeared when it was typed.
peaked during the 1980s, some systems The UNIX "talk" command shown in this screenshot was popular in the 1980s and
incorporated chat features which were early 1990s.

similar to instant messaging; Freelancin'
Roundtable was one prime example. The first[2] dedicated online chat service was the CompuServe CB Simulator in
1980,[3] created by CompuServe executive Alexander "Sandy" Trevor in Columbus, Ohio.

In the latter half of the 1980s and into the early 1990s, the Quantum Link online service for Commodore 64
computers offered user-to-user messages between currently connected customers, which they called "On-Line
Messages" (or OLM for short), and later "FlashMail." (Quantum Link later became America Online and made AOL
Instant Messenger (AIM), discussed later). While the Quantum Link service ran on a Commodore 64, using only the
Commodore's PETSCII text-graphics, the screen was visually divided up into sections and OLMs would appear as a
yellow bar saying "Message From:" and the name of the sender along with the message across the top of whatever
the user was already doing, and presented a list of options for responding.[4] As such, it could be considered a sort of
GUI (Graphical User Interface), albeit much more primitive than the later Unix, Windows and Macintosh based GUI
IM software. OLMs were what Q-Link called "Plus Services" meaning they charged an extra per-minute fee on top
of the monthly Q-Link access costs.
Modern, Internet-wide, GUI-based messaging clients as they are known today, began to take off in the mid 1990s
with PowWow, ICQ, and AOL Instant Messenger. Similar functionality was offered by CU-SeeMe in 1992; though
primarily an audio/video chat link, users could also send textual messages to each other. AOL later acquired
Mirabilis, the authors of ICQ; a few years later ICQ (now owned by AOL) was awarded two patents for instant
messaging by the U.S. patent office. Meanwhile, other companies developed their own software; (Excite, MSN,
Ubique, and Yahoo), each with its own proprietary protocol and client; users therefore had to run multiple client
applications if they wished to use more than one of these networks. In 1998, IBM released IBM Lotus Sametime, a
product based on technology acquired when IBM bought Haifa-based Ubique and Lexington-based Databeam.
In 2000, an open source application and open standards-based protocol called Jabber was launched. The protocol
was standardized under the name Extensible Messaging and Presence Protocol (XMPP). XMPP servers could act as
gateways to other IM protocols, reducing the need to run multiple clients. Multi-protocol clients can use any of the
popular IM protocols by using additional local libraries for each protocol. IBM Lotus Sametime's November 2007
release added IBM Lotus Sametime Gateway support for XMPP.
In the current era, social networking providers often offer IM capabilities.


Many instant messaging services offer video calling features, Voice Over IP (VoIP) and web conferencing services.
Web conferencing services can integrate both video calling and instant messaging capabilities. Some instant
messaging companies are also offering desktop sharing, IP radio, and IPTV to the voice and video features.
The term "Instant Messenger" is a service mark of Time Warner[5] and may not be used in software not affiliated
with AOL in the United States. For this reason, the instant messaging client formerly known as Gaim (or gaim)
announced, in April 2007, that they would be renamed "Pidgin".[6]

Clients
Each modern IM service generally provides its own client, either a separately installed piece of software, or a
browser-based client. These typically only work with that particular company's service, although some allow limited
function with other services. There are also third party client software applications that will connect with most of the
major IM services. Adium, Digsby, Jappix, Meebo, Miranda IM, Pidgin, Qnext and Trillian are a few of the common
ones.

Interoperability
Standard, complimentary instant messaging applications offer
functions like file transfer, contact list(s), the ability to hold
several simultaneous conversations, etc. These may be all the
functions that a small business needs, but larger organizations will
require more sophisticated applications that can work together.
The solution to finding applications capable of this is to use
enterprise versions of instant messaging applications. These
include titles like XMPP, Lotus Sametime, Microsoft Office
Communicator, etc., which are often integrated with other
enterprise applications such as workflow systems. These enterprise
applications, or Enterprise Application Integration (EAI), are built
to certain constraints, namely storing data in a common format.

There have been several attempts to create a unified standard for
Pidgin's tabbed chat window in Linux
instant messaging: IETF's SIP (Session Initiation Protocol) and
SIMPLE (SIP for Instant Messaging and Presence Leveraging
Extensions), APEX (Application Exchange), Prim (Presence and Instant Messaging Protocol), the open XML-based
XMPP (Extensible Messaging and Presence Protocol), and Open Mobile Alliance's Instant Messaging and Presence
Service developed specifically for mobile devices.

Most attempts at producing a unified standard for the major IM providers (AOL, Yahoo! and Microsoft) have failed,
and each continues to use its own proprietary protocol.
However, while discussions at IETF were stalled, Reuters signed the first inter-service provider connectivity
agreement on September 2003. This agreement enabled AIM, ICQ and MSN Messenger users to talk with Reuters
Messaging counterparts and vice-versa. Following this, Microsoft, Yahoo! and AOL agreed a deal in which
Microsoft's Live Communications Server 2005 users would also have the possibility to talk to public instant
messaging users. This deal established SIP/SIMPLE as a standard for protocol interoperability and established a
connectivity fee for accessing public instant messaging groups or services. Separately, on 13 October 2005,
Microsoft and Yahoo! announced that by the 3rd quarter of 2006 they would interoperate using SIP/SIMPLE, which
was followed, in December 2005, by the AOL and Google strategic partnership deal in which Google Talk users
would be able to communicate with AIM and ICQ users provided they have an AIM account.
There are two ways to combine the many disparate protocols:


• Combine the many disparate protocols inside the IM client application.
• Combine the many disparate protocols inside the IM server application. This approach moves the task of
communicating with the other services to the server. Clients need not know or care about other IM protocols. For
example, LCS 2005 Public IM Connectivity. This approach is popular in XMPP servers; however, the so-called
transport projects suffer the same reverse engineering difficulties as any other project involved with closed
protocols or formats.
Some approaches allow organizations to deploy their own, private instant messaging network by enabling them to
restrict access to the server (often with the IM network entirely behind their firewall) and administer user
permissions. Other corporate messaging systems allow registered users to also connect from outside the corporation
LAN, by using an encrypted, firewall-friendly, HTTPS-based protocol. Typically, a dedicated corporate IM server
has several advantages, such as pre-populated contact lists, integrated authentication, and better security and privacy.
Certain networks have made changes to prevent them from being utilized by such multi-network IM clients. For
example, Trillian had to release several revisions and patches to allow its users to access the MSN, AOL, and
Yahoo! networks, after changes were made to these networks. The major IM providers typically cite the need for
formal agreements as well as security concerns as reasons for making these changes.
The use of proprietary protocols has meant that many instant messaging networks have been incompatible and
people have been unable to reach friends on other networks. This has cost the instant messaging format dearly.[7]

Mobile instant messaging
Mobile Instant Messaging (MIM) is the technology that allows Instant Messaging services to be accessed from a
portable device, ranging from standard mobile phones, to smartphones (e.g. devices using operating systems such as
iOS, Blackberry OS, Symbian OS, Android OS, Windows Mobile, et al.). It is done two ways:
• Embedded Clients - tailored IM client for every specific device.
• Clientless Platform – a browser-based application that does not require downloading any software to the
handset, and which enables all users and all devices from any network to connect to their Internet IM service–
ideally. In practice, browser capabilities can pose problems.

In web browser
Gmail has instant messaging capacity in webpage itself, which can be used in a web browser without the need to
download and install the IM client. Later Yahoo and Hotmail also implemented it. eBuddy and Meebo websites
offers instant messaging of different IM services. Generally such services are limited to text chat, although Gmail
has voice and video capabilities. As of August 2010, Gmail allows the calling of regular phones from their
web-based IM client.
Jappix is a XMPP web-client, offering the user a complete XMPP protocol features access, through his web browser.
It is declined in three versions: a desktop one, a mobile one and a mini one. The last one, Jappix Mini, is a mini chat
for websites.


Friend-to-friend networks
Instant Messaging may be done in a Friend-to-friend network, in which each node connects to the friends on the
friends list. This allows for communication with friends of friends and for the building of chatrooms for instant
messages with all friends on that network.

IM language
Users sometimes make use of internet slang or text speak to abbreviate common words or expressions in order to
quicken conversations or to reduce keystrokes. The language has become universal, with well-known expressions
such as 'lol' translated over to face to face language.
Emotions are often expressed in shorthand, such as the abbreviation LOL, BRB and TTYL (respectively Laugh(ing)
Out Loud, Be Right Back and Talk To You Later).
Some, however, attempt to be more accurate with emotional expression over IM. Real time reactions such as
(chortle) (snort) (guffaw) or (eye-roll) are becoming more popular. Also there are certain standards that are being
introduced into mainstream conversations including, '#' indicates the use of sarcasm in a statement and '*' which
indicates a spelling mistake and/or grammatical error in the previous message, followed by a correction.[8]

Business application
Instant messaging has proven to be similar to personal computers, e-mail, and the World Wide Web, in that its
adoption for use as a business communications medium was driven primarily by individual employees using
consumer software at work, rather than by formal mandate or provisioning by corporate information technology
departments. Tens of millions of the consumer IM accounts in use are being used for business purposes by
employees of companies and other organizations.
In response to the demand for business-grade IM and the need to ensure security and legal compliance, a new type of
instant messaging, called "Enterprise Instant Messaging" ("EIM") was created when Lotus Software launched IBM
Lotus Sametime in 1998. Microsoft followed suit shortly thereafter with Microsoft Exchange Instant Messaging,
later created a new platform called Microsoft Office Live Communications Server, and released Office
Communications Server 2007 in October 2007. Oracle Corporation has also jumped into the market recently with its
Oracle Beehive unified collaboration software.[9] Both IBM Lotus and Microsoft have introduced federation between
their EIM systems and some of the public IM networks so that employees may use a single interface to both their
internal EIM system and their contacts on AOL, MSN, and Yahoo!. Current leading EIM platforms include IBM
Lotus Sametime, Microsoft Office Communications Server, Jabber XCP and Cisco Unified Presence. In addition,
industry-focused EIM platforms as Reuters Messaging and Bloomberg Messaging provide enhanced IM capabilities
to financial services companies.
The adoption of IM across corporate networks outside of the control of IT organizations creates risks and liabilities
for companies who do not effectively manage and support IM use. Companies implement specialized IM archiving
and security products and services to mitigate these risks and provide safe, secure, productive instant messaging
capabilities to their employees.


Review of products
IM products can typically be categorised into two types: Enterprise Instant Messaging (EIM)[10] and Consumer
Instant Messaging (CIM).[11] Enterprise solutions use an internal IM server, however this isn't always feasible,
particularly for smaller businesses with limited budgets. The second option, using a CIM provides the advantage of
being inexpensive to implement and has little need for investing in new hardware or server software.
For corporate use encryption and conversation archiving are usually regarded as important features due to security
concerns. Sometimes the use of different operating systems in organizations calls for the use of software that
supports more than one platform. For example many software companies use Windows XP in administration
departments but have software developers who use Linux.

Risks and liabilities
Although instant messaging delivers many benefits, it also carries with it certain risks and liabilities, particularly
when used in workplaces. Among these risks and liabilities are:
• Security risks (e.g. IM used to infect computers with spyware, viruses, trojans, worms)
• Compliance risks
• Inappropriate use
• Trade secret leakage

Security risks
Crackers (malicious "hacker" or [black hat] hacker) have consistently used IM networks as vectors for delivering
phishing attempts, "poison URLs", and virus-laden file attachments from 2004 to the present, with over 1100
discrete attacks listed by the IM Security Center[12] in 2004-2007. Hackers use two methods of delivering malicious
code through IM: delivery of viruses, trojan horses, or spyware within an infected file, and the use of "socially
engineered" text with a web address that entices the recipient to click on a URL connecting him or her to a website
that then downloads malicious code. Viruses, computer worms, and trojans typically propagate by sending
themselves rapidly through the infected user's buddy list. An effective attack using a poisoned URL may reach tens
of thousands of people in a short period when each person's buddy list receives messages appearing to be from a
trusted friend. The recipients click on the web address, and the entire cycle starts again. Infections may range from
nuisance to criminal, and are becoming more sophisticated each year.
IM connections usually take place in plain text, making them susceptible to eavesdropping. In addition, IM client
software often requires the user to expose open UDP ports to the world, increasing the threat posed by potential
security vulnerabilities.[13]

Compliance risks
In addition to the malicious code threat, the use of instant messaging at work also creates a risk of non-compliance to
laws and regulations governing the use of electronic communications in businesses. In the United States alone there
are over 10,000 laws and regulations related to electronic messaging and records retention.[14] The better-known of
these include the Sarbanes-Oxley Act, HIPAA, and SEC 17a-3. Clarification from the Financial Industry Regulatory
Authority ("FINRA") was issued to member firms in the financial services industry in December, 2007, noting that
"electronic communications", "email", and "electronic correspondence" may be used interchangeably and can
include such forms of electronic messaging as instant messaging and text messaging.[15] Changes to Federal Rules of
Civil Procedure, effective December 1, 2006, created a new category for electronic records which may be requested
during discovery in legal proceedings. Most countries around the world also regulate the use of electronic messaging
and electronic records retention in similar fashion to the United States. The most common regulations related to IM
at work involve the need to produce archived business communications to satisfy government or judicial requests


under law. Many instant messaging communications fall into the category of business communications that must be
archived and retrievable.

Inappropriate use
Organizations of all types must protect themselves from the liability of their employees' inappropriate use of IM. The
informal, immediate, and ostensibly anonymous nature of instant messaging makes it a candidate for abuse in the
workplace. The topic of inappropriate IM use became front page news in October 2006 when U.S. Congressman
Mark Foley resigned his seat after admitting sending offensive instant messages of a sexual nature to underage
former House pages from his Congressional office PC. The Mark Foley Scandal led to media coverage and
mainstream newspaper articles warning of the risks of inappropriate IM use in workplaces. In most countries,
corporations have a legal responsibility to ensure harassment-free work environment for employees. The use of
corporate-owned computers, networks, and software to harass an individual or spread inappropriate jokes or
language creates a liability for not only the offender but also the employer. A survey by IM archiving and security
provider Akonix Systems, Inc. in March 2007 showed that 31% of respondents had been harassed over IM at
work.[16] Companies now include instant messaging as an integral component of their policies on appropriate use of
the World Wide Web, e-mail, and other corporate assets.

Security and archiving
In the early 2000s, a new class of IT security provider emerged to provide remedies for the risks and liabilities faced
by corporations who chose to use IM for business communications. The IM security providers created new products
to be installed in corporate networks for the purpose of archiving, content-scanning, and security-scanning IM traffic
moving in and out of the corporation. Similar to the e-mail filtering vendors, the IM security providers focus on the
risks and liabilities described above.
With rapid adoption of IM in the workplace, demand for IM security products began to grow in the mid-2000s. By
2007, the preferred platform for the purchase of security software had become the "computer appliance", according
to IDC, who estimate that by 2008, 80% of network security products will be delivered via an appliance.[17]

User base
Note that many of the numbers listed in this section are not directly comparable, and some are speculative. While
some numbers are given by the owners of a complete instant messaging system, others are provided by commercial
vendors of a part of a distributed system. Some companies may be motivated to inflate their numbers in order to
increase advertisement earnings or to attract partners, clients, or customers. Importantly, some numbers are reported
as the number of "active" users (without a shared standard of that activity), others indicate total user accounts, while
others indicate only the users logged in during an instance of peak usage.

Service User count Date/source

AIM 53 million active [18]
September 2006

>100 million total [19]
January 2006

eBuddy 35 million total [20]
October 2006 , including 4 million mobile users

Gadu-Gadu Over 6 million active (majority in Poland) [21]
May 2009

IBM Lotus Sametime 40 million total (licensed, entitled users in December 2009
enterprises)

ICQ 50 million active [22]
CNET February 8, 2010

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