electronic-mail(unit-1)

UNIT – 1 Electronic-Mail

Introduction

E-mail stands for electronic mail which is the transmission of messages over communications networks. The messages can be notes entered from the keyboard or electronic files stored on disk.
Some electronic-mail systems are limited to a single computer system or network, but others have gateways to other computer systems, enabling users to send electronic mail anywhere in the world. Companies that are fully computerized make extensive use of e-mail because it is fast, flexible, and reliable.
Most e-mail systems include a simple text editor for composing messages, but many allow you to edit your messages using any editor you want. You then send the message to the recipient by specifying the recipient's address. You can also send the same message to several users at once. This is called broadcasting.
ORIGIN of E-mail:
The ARPANET computer network made a large contribution to the development of e-mail. There is one report that indicates experimental inter-system e-mail transfers began shortly after its creation in 1969. Ray Tomlinson initiated the use of the @ sign to separate the names of the user and their machine in 1971. The ARPANET significantly increased the popularity of e-mail, and it became the killer app of the ARPANET.

Advantages and disadvantages

Advantages of E-mail:
Email is Fast
Mail is delivered instantly...from your office to anywhere in the world. No other method of delivery can provide this service. Timely buying and selling decisions can be made in a heartbeat.
2. Email is Inexpensive
Compared to telephone calls, faxes, or over night courier service, Email is less expensive.
3. Managing Email is Easy
You can manage all your correspondence on screen and so can your customers. Your proposal can be answered, revised, stored, and sent to others, all without reams of paper involved.

4. Email is Easy to Filter
The subject line on an Email makes it easy to prioritize messages. The reader can identify ritical correspondence quickly and dealt with it immediately. Unlike regular mail which needs to be opened and reviewed, or voice mail which requires you to either listen to or scan all your messages for those that require immediate attention.
5. Transmission is Secure and Reliable
The level of security in transmitting Email messages is very high, and the industry continues to strive to develop even tighter security levels. Email is private. Often telephone and fax messages are not. If the address information is correct, rarely does an Email go astray. Fax machines can be out of order or out of paper and this prevents an important message from being delivered in a timely manner.

Disadvantages to using e-mail:
Lack of security, particularly with regards to Web-based e-mail and shared computers.
Informal method of communication. Not always suitable for serious business documents or transactions requiring signatures.
Due to its informal nature it is easy to ignore - unlike communication on the telephone or mail.
Spam. Unsolicited junk mail is easier to send than conventional mail and harder to trace back to the sender.
Too much e-mail can lead to management problems with your in-box being overwhelmed by mail.


User-ids, Pass words

User ID/Name: Used to identify a user. A code made up by the user that allows access to a Web site, software program, or computer. It is a name that is used to associate the user profile with a user when a user signs on to a system.

Password: It is a word or string of characters that is entered, often along with a user name/ID, into a computer system to log in or to access some resource. It is a secret word or phrase known only to a restricted group.


E-mail addresses
E-mail Address:
It is a unique identifier specifying a virtual location to which e-mail can be sent. E-mail address has three parts.
The first part is your username. You set up the username with your Internet provider or e-mail service. It might be a form of your name. It might be a nickname. If you are an antique collector, your username might be antique_ fan. It is at this point that your provider or service makes sure no one else on their system already has that name.
The second part of your e-mail address is the @ (at) symbol
The third part, which is the name of the computer that handles your mail. This computer is also called a server. Your Internet Service Provider (ISP) or e-mail service has a particular name for their server - like aol.com for America Online or yahoo.com for those who go through the Yahoo service. Hotmail.com is an example of a free web-based e-mail service
Examlpe: antique_fan@hotmail.com
Where:
Antique_fan is the user-name.
Hotmail.com is the domain name of the E-mail server.

Message Components
Components of an email message
An email message consists of the following general components:
1. Headers
The message headers contain information concerning the sender and recipients. The exact content of mail headers can differ depending on the email system that generated the message. Generally, headers contain the following information:
· Subject. This describes what a message is about. For example if you are sending a message about a schedule of an exam then it might be “Exam schedule”.
· Sender (From). This is the senders Internet email address. It is usually assumed to be the same as the Reply-to address, unless a different one is provided.
· Date and time received (On). The time the message was received.
· Reply-to. This is the Internet email address that will become the recipient of your reply if you click the Reply button.
· Recipient (To:). First/last name of email recipient, as configured by the sender.
· Recipient email address. The Internet mail address of the recipient, or where the message was actually sent.
2. Body
The body of a message contains text that is the actual content. The message body also may include signatures or automatically generated text that is inserted by the sender's email system.
3. Attachments
These are optional and include any separate files that may be part of the message.
Composing an E-Mail Message
E-mail addresses must be letter-perfect in order for your mail to reach the intended destination, and Outlook Express is rich with options for addressing messages accurately. You type a few letters of the person's name in the To or CC (for carbon copy) lines, and then Outlook Express automatically supplies the full address from your address book.
1. Click the Create Mail button.

2. In the To box, type the first few letters of your recipient's name as shown below. When Outlook Express proposes the name you want, press the Enter key.
If the name isn't in your address book, type the complete e-mail address. Capitalization doesn't matter, and there should be no spaces in the address.
3. Repeat step 2 for each person you want to send the message to, separating names with a comma or semi-colon.
4. To send copies of your e-mail, follow steps 2 and 3 above in the CC box as shown below for each person who will get a copy.
To and CC fields on a new mail message.
5. Type a brief subject for your message as shown below.
Outlook Express will remind you if you forget this.
6. Click in the message area, and type your message as shown below.
7. Click Send as shown below.
If Outlook Express asks for confirmation of any name, click the correct name in the Check Names box, and click OK.



Write an E-Mail Message, Send It Later
You can compose e-mail while your computer is disconnected from the Internet.
Follow the steps in the Composing an E-Mail Message, section above.
When you click Send, Outlook Express lets you know that it's storing your message in the Outbox—it's in the Folder list—and then sends it automatically when you go online.
Save your e-mail. Outlook Express also automatically saves messages as you write them, so if your computer shuts down unexpectedly, your messages will be waiting for you in the Drafts folder. But for extra safety, it's not a bad idea—particularly for an important message—to save your e-mail message as you write. To do this, click Save, on the File menu.


Attach a File to an E-Mail Message

It's easy to attach files to e-mail—a picture of the new baby, the paper you're coauthoring, your tax file for the accountant, or a favorite song. It's rather like paper-clipping something to a letter.
1. In your message, click the Attach button.
2. Browse until you find the file you want to attach as shown below.
3. Click the file, and then click Attach as shown below.
If you want to enclose more than one file, repeat steps 1 through 3.
4. Finish the message if you haven't already, and click the Send button.
5. The attachments show up (!) here in the message.
Insert a File to an E-Mail Message(Inline Attachments)
Email can be formatted to include the images in-line. That means part of what determines how the email is displayed is exactly what format the sender used to compose their email.
· HTML and Rich Text formatted email both allow images to be embedded/inserted within the actual message. Naturally, there are different ways to do this; for example the image can be included within the email as an attachment to be displayed within the message, or the image can be linked to from a web site. Both formats also allow images to simply be included as regular attachments without any relationship to the message body.

· Plain text email, on the other hand, only allows for images as attachments.


Personalize Your E-Mail Messages with signatures

You can put your singular stamp on e-mail. With Outlook Express you can use a distinctive personal signature.
Create a Personal Signature for All Messages
One advantage of the letterhead on business papers is that you don’t have to repeat information on every piece of correspondence. You can duplicate that advantage in e-mail by creating a special signature that doubles as letterhead and signature. Outlook can then append it automatically to new messages, or you can sign each one individually.
1. On the Outlook Express Tools menu, click Options, and then click the Signatures tab.
2. Click the New button as shown below.
3. Type your signature as you want it to appear as shown below.
4. If you want this signature on all your e-mail (except replies and forwards), check Add signatures to all outgoing messages (shown below).
5. When you're finished, click OK.Now every e-mail message you start will have this signature.
Add Your Signature to individual Messages

Although Outlook Express is smart about not adding your signature when you reply to an e-mail message or forward it, you may want more control over when your full signature is added. Maybe you've created a business-like signature, and don't want it on messages to friends and family. Or perhaps you have two signatures—one for business and one for more personal correspondence. In such situations, follow the steps below to add a signature you've already created, message by message.

1. On the Outlook Express Tools menu, click Options, and then click the Signatures tab.
2. Make sure that the Add signatures to all outgoing messages check box is clear, and click OK.
3. Compose your e-mail message.
4. To sign your message, click the Insert menu on the e-mail message, point to Signature, and then click your signature.


Mailer features

eMailer is a personalized group mailer that can be used as a powerful marketing tool to send personalized targeted mails. eMailer helps you to reach out to your customers by sending targeted mails, with each recipient receiving a personalized copy of the mail. eMailer is a powerful and fast mass mailer that can be used to manage your email campaigns.
Features are as follow:
· Personalized Mails
Personalize each mails based on any header. Each lists is mapped to a CSV file, and the mail send to that list can be personalized on any of the header present in that CSV file.
· Direct Mailing
No need to add all your customers email addresses together. Just create a subscription list, include all the subscribers, and send a single mail to that list. eMailer will in turn send that mail directly to each of the subscribers.
· No SMTP required
Don't have an SMTP server? Don't worry. eMailer can talk directly with the recipient mail server and deliver the mails.
If you have an SMTP server and want to route the mails through it, just configure eMailer. It even supports SSL mail servers.
· Unlimited Subscription Lists
Create as must subscription lists as you want. Its just a matter of importing a CSV file! You can also create any number of sender accounts.
· HTML / Plain Text Mails
Send HTML or Plain Text mails easily. eMailer contains a WYSIWYG HTML editor, which allows you to create HTML mails easily.
· Drag and Drop Attachments
Attaching a file is just a matter of drag and drop. Attach any number of files easily.
· Emoticons Support
eMailer supports a wide range of emoticons. It can be easily extended to add your own set of emoticons/smileys.
· Platform Independence
eMailer can run on any OS that supports Java like Windows, Mac, Linux, etc.
· Fast Delivery
You decide how fast it should be. eMailer is completely configurable.




E-mail inner working






Step A: Sender creates and sends an email
The originating sender creates an email in their Mail User Agent (MUA) and clicks 'Send'. The MUA is the application the originating sender uses to compose and read email, such as Eudora, Outlook, etc.

Step B: Sender's MDA/MTA routes the email
The sender's MUA transfers the email to a Mail Delivery Agent (MDA). Frequently, the sender's MTA also handles the responsibilities of an MDA. Several of the most common MTAs do this, including sendmail and qmail.
The MDA/MTA accepts the email, then routes it to local mailboxes or forwards it if it isn't locally addressed

Step C: Network Cloud
An email can encounter a network cloud within a large company or ISP, or the largest network cloud in existence: the Internet.network cloud may encompass a multitude of mail servers, DNS servers, routers, and other devices and services too numerous to mention. These devices may be protected by firewalls, spam filters and malware detection software that may bounce or even delete an email. When an email is deleted by this kind of software, it tends to fail silently, so the sender is given no information about where or when the delivery failure occurred.
Email service providers and other companies that process a large volume of email often have their own, private network clouds. These organizations commonly have multiple mail servers, and route all email through a central gateway server (i.e., mail hub) that redistributes mail to whichever MTA is available. Email on these secondary MTAs must usually wait for the primary MTA (i.e., the designated host for that domain) to become available, at which time the secondary mail server will transfer its messages to the primary MTA.

Step D: Email Queue
The email in the diagram is addressed to someone at another company, so it enters an email queue with other outgoing email messages. If there is a high volume of mail in the queue—either because there are many messages or the messages are unusually large, or both—the message will be delayed in the queue until the MTA processes the messages ahead of it.




Step E: MTA to MTA Transfer
When transferring an email, the sending MTA handles all aspects of mail delivery until the message has been either accepted or rejected by the receiving MTA.
As the email clears the queue, it enters the Internet network cloud, where it is routed along a host-to-host chain of servers. Each MTA in the Internet network cloud needs to "stop and ask directions" from the Domain Name System (DNS) in order to identify the next MTA in the delivery chain. The exact route depends partly on server availability and mostly on which MTA can be found to accept email for the domain specified in the address. Most email takes a path that is dependent on server availability, so a pair of messages originating from the same host and addressed to the same receiving host could take different paths. These days, it's mostly spammers that specify any part of the path, deliberately routing their message through a series of relay servers in an attempt to obscure the true origin of the message.
To find the recipient's IP address and mailbox, the MTA must drill down through the Domain Name System (DNS), which consists of a set of servers distributed across the Internet. Beginning with the root nameservers at the top-level domain (.tld), then domain nameservers that handle requests for domains within that .tld, and eventually to nameservers that know about the local domain.

Step F: Firewalls, Spam and Virus Filters
The transfer process described in the last step is somewhat simplified. An email may be transferred to more than one MTA within a network cloud and is likely to be passed to at least one firewall before it reaches it's destination.
An email encountering a firewall may be tested by spam and virus filters before it is allowed to pass inside the firewall. These filters test to see if the message qualifies as spam or malware. If the message contains malware, the file is usually quarantined and the sender is notified. If the message is identified as spam, it will probably be deleted without notifying the sender.
Spam is difficult to detect because it can assume so many different forms, so spam filters test on a broad set of criteria and tend to misclassify a significant number of messages as spam, particularly messages from mailing lists. When an email from a list or other automated source seems to have vanished somewhere in the network cloud, the culprit is usually a spam filter at the receiver's ISP or company. This explained in greater detail in Virus Scanning and Spam Blocking.

Delivery
In the diagram, the email makes it past the hazards of the spam trap...er...filter, and is accepted for delivery by the receiver's MTA. The MTA calls a local MDA to deliver the mail to the correct mailbox, where it will sit until it is retrieved by the recipient's MUA.

E-mail Management

Some basic E-mail management rules are:
1) Let your email program manage your email as much as possible.Email management starts with setting up and using filters. If you're using an email program such as Outlook, you can configure email rules to send your spam directly to the trash - meaning that you don't waste your time reading and deleting it.
2) Do not check your email on demand.You don't need to see every piece of email the second it arrives. If you're using an email program that announces the arrival of new email, turn off the program's announcement features, such as making a sound or having a pop-up screen announce the arrival of email. Checking email on demand can seriously interfere with whatever other tasks you're trying to accomplish because most people will read email when they check it.
3) Don't read and answer your email all day long.You may get anywhere from a handful to hundreds of emails each day that need to be answered, but they don't need to be answered immediately, interrupting whatever else you're doing. Instead, set aside a particular time each day to review and answer your email. Schedule the hour or whatever time it takes you to answer the volume of email you get, and stick to that schedule as regularly as possible.
4) Don't answer your email at your most productive time of day.Most productive work time is the morning. If you start your work day by answering your email, you lose the time that you are at my most creative. If you are writing a message, it will take twice as long to compose it in the afternoon or evening than it would in the morning, when you feel fresh and alert.
Answering email, on the other hand, isn't usually a task that calls for a great deal of creativity. So by ignoring you email until the late afternoon, and answering it then, you get the dual benefit of saving your productive time for other more demanding tasks, and not continually interrupting whatever other tasks you are trying to accomplish.
MIME Types
Why need MIME (Multipurpose internet mail extension)
The basic Internet e-mail transmission protocol, SMTP, supports only 7-bit ASCII characters. This effectively limits Internet e-mail to messages which, when transmitted, include only the characters sufficient for writing a small number of languages, primarily English. Other languages based on the Latin alphabet typically include diacritics not supported in 7-bit ASCII, meaning text in these languages cannot be correctly represented in basic e-mail..
Multipurpose Internet Mail Extensions (MIME) is an Internet standard that extends the format of e-mail to support:
text in character sets other than ASCII.
non-text attachments.
message bodies with multiple parts .
header information in non-ASCII character sets.
Mapping messages into and out of MIME format is typically done automatically by an e-mail client or by mail servers when sending or receiving Internet e-mail.Virtually all human-written Internet e-mail and a fairly large proportion of automated e-mail is transmitted via SMTP in MIME format. Internet e-mail is so closely associated with the SMTP and MIME standards that it is sometimes called SMTP/MIME e-mail.
The basic format of Internet (SMTP/MIME) e-mail is defined in RFC 2822
MIME Header Fields
1. MIME-Version
2. Content-Type
3. Content-Disposition
4. Content-Transfer-Encoding
5. Encoded-Word
1. MIME-Version
The presence of this header indicates the message is MIME-formatted. The value is typically "1.0" so this header appears as
It should be noted that implementers have attempted to change the version number in the past and the change had unforeseen results. It was decided at an IETF meeting to leave the version number as is even though there have been many updates and versions of MIME.
2. Content-Type
This header indicates the Internet media type of the message content, consisting of a type and subtype, for example
Through the use of the multipart type, MIME allows messages to have parts arranged in a tree structure where the leaf nodes are any non-multipart content type and the non-leaf nodes are any of a variety of multipart types. This mechanism supports:
simple text messages using text/plain (the default value for "Content-type:")
text plus attachments (multipart/mixed with a text/plain part and other non-text parts). A MIME message including an attached file generally indicates the file's original name with the "Content-disposition:" header, so the type of file is indicated both by the MIME content-type and the filename extension
reply with original attached (multipart/mixed with a text/plain part and the original message as a message/rfc822 part)
alternative content, such as a message sent in both plain text and another format such as HTML (multipart/alternative with the same content in text/plain and text/html forms)
image, audio, video and application (for example, image/jpg, audio/mp3, video/mp4, and application/msword and so on)
many other message constructs
3. Content-Disposition
The specification of content-disposition attempted to provide a means of providing file name information by defining a filename parameter as part of the content-disposition field.

4. Content-Transfer-Encoding
MIME defined a set of methods for representing binary data in ASCII text format. The content-transfer-encoding: MIME header has 2-sided significance:
It indicates whether or not a binary-to-text encoding scheme has been used on top of the original encoding as specified within the Content-Type header, and
If such a binary-to-text encoding method has been used it states which one.
Options:
7-Bit - Data is sent as US-ASC data.
8-Bit - 8 bit characters are included in short lines.
BASE64 - Used for binary files. Three bytes are transformed into 4 ASC characters in lines limited to a length of 76 characters.
Binary - Long lines are sent using 8 bit characters. These lines may not be transportable using SMTP.
Quoted-Printable - Used tor ASC text. Line length is limited to 76 characters.
X-Token - Defines private encoding values prefixed with an "X-".

5. Encoded-Word
Since message header names and values are always ASCII characters, values that contain non-ASCII data must use the MIME encoded-word syntax instead of a literal string. This syntax uses a string of ASCII characters indicating both the original character encoding and the content-transfer-encoding used to map the bytes of the charset into ASCII characters.
The form is: "=?charset?encoding?encoded text?=".
charset may be any character set registered with IANA(Internet Assigned Numbers Authority). Typically it would be the same charset as the message body.
encoding can be either "Q" denoting Q-encoding that is similar to the quoted-printable encoding, or "B" denoting base64 encoding.
encoded text is the Q-encoded or base64-encoded text.
The encoded-word format is not used for the names of the headers (for example Subject). These header names are always in English in the raw message. When viewing a message with a non-English e-mail client, the header names are usually translated by the client
Multipart messages
A MIME multipart message contains a boundary in the "Content-type:" header. This boundary, must not occur in any of the parts. It is placed between the parts, and at the beginning and end of the body of the message, as follows:
Each part consists of its own content header and a body. Multipart content can be nested. The content-transfer-encoding of a multipart type must always be "7bit", "8bit" or "binary" to avoid the complications that would be posed by multiple levels of decoding.
Multipart subtypes
The MIME standard defines various multipart-message subtypes, which specify the nature of the message parts and their relationship to one another. The subtype is specified in the "Content-Type" header of the overall message. For example, a multipart MIME message using the digest subtype would have its Content-Type set as "multipart/digest".
The following is a list of the most commonly used subtypes; it is not intended to be a comprehensive list.
1. Mixed
Multipart/mixed is used for sending files with different "Content-Type" headers inline (or as attachments). If sending pictures or other easily readable files, most mail clients will display them inline (unless otherwise specified with the "Content-disposition" header). Otherwise it will offer them as attachments. The default content-type for each part is "text/plain".
2. Message
A message/rfc822 part contains an email message, including any headers. Rfc822 is a Standard for ARPA Internet Text Messages since the message may be a full MIME message. This is used for digests as well as for E-mail forwarding.
3. Digest
Multipart/digest is a simple way to send multiple text messages. The default content-type for each part is "message/rfc822".
4. Alternative
The multipart/alternative subtype indicates that each part is an "alternative" version of the same (or similar) content, each in a different format denoted by its "Content-Type" header. Systems can then choose the "best" representation they are capable of processing; in general, this will be the last part that the system can understand.
Since a client is unlikely to want to send a version that is less faithful than the plain text version this structure places the plain text version (if present) first. This makes it easier for users of clients that do not understand multipart messages.
Most commonly multipart/alternative is used for email with two parts, one plain text (text/plain) and one HTML (text/html). The plain text part provides backwards compatibility while the HTML part allows use of formatting and hyperlinks. Most email clients offer a user option to prefer plain text over HTML, this is an example of how local factors may affect how an application chooses which "best" part of the message to display.
5. Related
A multipart/related is used to indicate that message parts should not be considered individually but rather as parts of an aggregate whole. The message consists of a root part (by default, the first) which reference other parts inline, which may in turn reference other parts. Message parts are commonly referenced by the "Content-ID" part header. The syntax of a reference is unspecified and is instead dictated by the encoding or protocol used in the part.
One common usage of this subtype is to send a web page complete with images in a single message. The root part would contain the HTML document, and use image tags to reference images stored in the latter parts.
6. Report
Multipart/report is a message type that contains data formatted for a mail server to read. It is split between a text/plain (or some other content/type easily readable) and a message/delivery-status, which contains the data formatted for the mail server to read.
7. Signed
A multipart/signed message is used to attach a digital signature to a message. It has two parts, a body part and a signature part. The whole of the body part, including mime headers, is used to create the signature part. Many signature types are possible, like application/pgp-signature and application/x-pkcs7-signature.
8. Encrypted
A multipart/encrypted message has two parts. The first part has control information that is needed to decrypt the application/octet-stream second part. Similar to signed messages, there are different implementations which are identified by their separate content types for the control part. The most common types are "application/pgp-encrypted" and "application/pkcs7-mime".
9. Form Data
As its name implies, multipart/form-data is used to express values submitted through a form. Originally defined as part of HTML 4.0, it is most commonly used for submitting files via HTTP.
10. Mixed-Replace (Experimental)
The content type multipart/x-mixed-replace was developed as part of a technology to emulate server push and streaming over HTTP.
All parts of a mixed-replace message have the same semantic meaning. However, each part invalidates - "replaces" - the previous parts as soon as it is received completely. Clients should process the individual parts as soon as they arrive and should not wait for the whole message to finish.
11. Byteranges
The multipart/byteranges is used to represent noncontiguous byte ranges of a single message. It is used by HTTP when a server returns multiple byte ranges


Newsgroups

A newsgroup is a repository usually within the Usenet system, for messages posted from many users in different locations. The term may be confusing to some, because it is usually a discussion group. Newsgroups are technically distinct from, but functionally similar to, discussion forums on the World Wide Web. Newsreader software is used to read newsgroups.
Typically, a newsgroup is focused on a particular topic. Some newsgroups allow the posting of messages on a wide variety of themes, regarding anything a member chooses to discuss as on-topic, while others keep more strictly to their particular subject, frowning on off-topic postings. The news admin (the administrator of a news server) decides how long articles are kept before being expired (deleted from the server). Usually they will be kept for one or two weeks, but some admins keep articles in local or technical newsgroups around longer than articles in other newsgroups.
Newsgroups are much like the public message boards on old bulletin board systems. For those readers not familiar with this concept, envision an electronic version of the corkboard in the entrance of your local grocery store.
Moderated and unmoderated newsgroups
A minority of newsgroups are moderated. That means that messages submitted by readers are not distributed to Usenet, but instead are emailed to the moderators of the newsgroup, for approval. Moderated newsgroups have rules called charters. Moderators are persons whose job is to ensure that messages that the readers see in newsgroups conform to the charter of the newsgroup. Typically, moderators are appointed in the proposal for the newsgroup, and changes of moderators follow a succession plan.
The job of the moderator is to receive submitted articles, review them, and inject approved articles so that they can be properly propagated worldwide. Such articles must bear the Approved: header line.
Unmoderated newsgroups form the majority of Usenet newsgroups, and messages submitted by readers for unmoderated newsgroups are immediately propagated for everyone to see.
Creation of moderated newsgroups often becomes a hot subject of controversy, raising issues regarding censorship and the desire of a subset of users to form an intentional community.
How newsgroups work:
Newsgroup servers are hosted by various organizations and institutions. Most Internet service providers (ISPs) host their own news servers, or rent access to one, for their subscribers. There are also a number of companies who sell access to premium news servers.
Every host of a news server maintains agreements with other news servers to regularly synchronize. In this way news servers form a network. When a user posts to one news server, the message is stored locally. That server then shares the message with the servers that are connected to it if both carry the newsgroup, and from those servers to servers that they are connected to, and so on. For newsgroups that are not widely carried, sometimes a carrier group is used for crossposting to aid distribution. This is typically only useful for groups that have been removed or newer alt.* groups. Crossposts between hierarchies, outside of the Big 8 and alt.* hierarchies, are failure prone. Njjh
Hierarchies:
Newsgroups are often arranged into hierarchies, theoretically making it simpler to find related groups. The term top-level hierarchy refers to the hierarchy defined by the prefix prior to the first dot.
The most commonly known hierarchies is the usenet hierarchies. So for instance newsgroup rec.arts.sf.starwars.games would be in the rec.* top-level usenet hierarchy, where the asterisk (*) is defined as a wildcard character. There were seven original major hierarchies of usenet newsgroups, known as the "Big 7":
comp.* — Discussion of computer-related topics
news.* — Discussion of Usenet itself
sci.* — Discussion of scientific subjects
rec.* — Discussion of recreational activities (e.g. games and hobbies)
soc.* — Socialising and discussion of social issues.
talk.* — Discussion of contentious issues such as religion and politics.
misc.* — Miscellaneous discussion—anything which doesn't fit in the other hierarchies.
Further hierarchies
There are a number of newsgroup hierarchies outside of the Big 8 (and alt.*) that can be found at many news servers. These include non-English language groups, groups managed by companies or organizations about their products, geographic/local hierarchies, and even non-internet network boards routed into NNTP. Examples include (alphabetically):
aus.* — Australian news groups
ba.* — Discussion in the San Francisco Bay area
ca.* — Discussion in California
can.* — Canadian news groups
cn.* — Chinese news groups
chi.* — Discussions about the Chicago area
de.* — Discussions in German
england.* — Discussions (mostly) local to England, see also uk.*
fidonet.* — Discussions routed from FidoNet
fr.* — Discussions in French
fj.* — "From Japan," discussions in Japanese
gnu.* — Discussions about GNU software
hawaii.* — Discussions (mostly) local to Hawaii
harvard.* — Discussions (mostly) local to Harvard
hp.* — Hewlett-Packard internal news groups
it.* — Discussions in Italian
microsoft.* — Discussions about Microsoft products
pl.* — Polish news groups
tw.* — Taiwan news groups
uk.* — Discussions on matters in the UK
Additionally, there is the free.* hierarchy, which can be considered "more alt than alt.*". There are many local sub-hierarchies within this hierarchy, usually for specific countries or cultures (such as free.it.* for Italy).

Subscibing to a newsgroup
Before you can subscribe to Internet newsgroups, you must configure Outlook Express for Internet news.
Configuring Outlook Express for Internet news
Outlook Express 4.x0
1. In Outlook Express, click Accounts on the Tools menu.
2. In the Internet Accounts dialog box, click Add, and then click News.
3. In the Display Name box, type the name you want other people to see when you post a message, and then click Next.
4. In the E-mail Address box, type the e-mail address for the account you are using (for example, janedoe@account.com), and then click Next.
5. In the News (NNTP) Server box, type the name of your Internet news server. If you are required to log on, click the My news server requires me to log on check box to select it. Click Next.
6. If you are required to log on, type your account name and password for your news server in the News Account Name and Password boxes, or click Log on using Secure Password Authentication (SPA). Choose the method recommended by your ISP. MSN requires SPA when when using the netnews.msn.com MSN news server.
7. In the Internet News Account Name, type a name that identifies the news account you are configuring (this is the "friendly" name for the news account), and then click Next.
8. Click the connection type that you use to connect to the Internet, and then click Next.
9. If you click Use my phone line to connect, you are prompted to either create a new Dial-Up Networking connection or use an existing one. If Dial-Up Networking has been configured for your ISP, click Use an existing dial-up connection, click the name for your Dial-Up Networking connection in the list, and then click Next.
10. If you click Connect using my local area network (LAN) or I will establish my Internet connection manually, you are not prompted for any additional settings.
11. Click Finish.

Outlook Express 5
1. In Outlook Express, click Accounts on the Tools menu.
2. In the Internet Accounts dialog box, click Add, and then click News.
3. In the Display Name box, type a friendly name for the newsgroup, and then click Next.
4. In the E-mail Address box, type the e-mail address for the account you are using (for example, janedoe@account.com), and then click Next.
5. In the News (NNTP) Server box, type the name of your Internet news server. If you are required to log on, click the My news server requires me to log on check box to select it. Click Next.
6. If you are required to log on, type your account name and password for your news server in the News Account Name and Password boxes, or click Log on using Secure Password Authentication (SPA). Choose the method recommended by your ISP. MSN requires SPA when when using the netnews.msn.com MSN news server.

7. Click Next in the Congratulations screen, and then click Finished. You can now set your default newsgroup,or click Close.
8. To set up your default News account, on the Tools menu, click Accounts. Click the News tab, click the account name you want as the default and then click Set As Default.
9. To select your connection method for the account, click Properties, click the Connection tab, and then from the list click to select either your local area network (LAN) or a dial-up connection.
10. Click OK and then Close to save all settings.

Subscribing to newsgroups using Outlook Express:
On the Tools menu, click Accounts.
Click Add, and then click News.
Enter your name as you wish it to be displayed in the newsgroups. Some people use their real names and some use nicknames - it's entirely up to you. Then click 'Next'.

Enter your email address. Then click 'Next'

Enter the name of the news server, which should be news.btinternet.com. Then click 'Next'


Click 'Finish'
Click 'Close' on the accounts window
If this is the first time you have set up this account in Outlook Express you will be asked 'Would you like to download newsgroups from the news account you added?' Click 'Yes'.
The list of newsgroups available through the BT Yahoo! Internet news server will then be downloaded. This can take some time, as there are many thousands of groups available. Once the headers are downloaded you can select which groups you wish to subscribe to. To narrow down your search, enter text in the box entitled 'Display newsgroups which contain' - for example, you could type 'bt'
Highlight your chosen newsgroup(s), then click on 'Subscribe'. An icon will appear beside each newsgroup you've selected. Then click 'OK'
You'll now see an extra folder in your folder list called news.btinternet.com with your subscriptions below it. Click on one of the newsgroups you subscribe to and the last 300 messages will download.

Reading and replying to messages
The last messages in the list are the most recent. Messages you have not read are in bold.
To reply to a message, make sure you have the correct one highlighted and click on the reply button at the top, as shown below.

The reply window will appear. Scroll to the bottom to add your comments. It may take up to 5 minutes for your post to appear on the newsgroup.
To see the latest posts, you may need to click on the 'synchronise' button.





Mailing Lists

A mailing list is a collection of names and addresses used by an individual or an organization to send material to multiple recipients. The term is often extended to include the people subscribed to such a list, so the group of subscribers is referred to as "the mailing list", or simply "the list".
An electronic mailing list (sometimes written as elist or e-list) is a special usage of e-mail that allows for widespread distribution of information to many Internet users. It is similar to a traditional mailing list — a list of names and addresses — as might be kept by an organization for sending publications to its members or customers, but typically refers to four things:
· A list of e-mail addresses,
· The people ("subscribers") receiving mail at those addresses
· The publications (e-mail messages) sent to those addresses
· And a reflector, which is a single e-mail address that, when designated as the recipient of a message, will send a copy of that message to all of the subscribers.
How automated electronic mailing lists work:
Electronic mailing lists are usually fully or partially automated through the use of special mailing list software and a reflector address that are set up on a server capable of receiving e-mail. Incoming messages sent to the reflector address are processed by the software, and, depending on their content, are acted upon internally (in the case of messages containing commands directed at the software itself) or are distributed to all e-mail addresses subscribed to the mailing list. Depending on the software, additional addresses may be set up for the purpose of sending commands. Many electronic mailing list servers have a special email address in which subscribers (or those that want to be subscribers) can send commands to the server to perform such tasks as subscribing and unsubscribing, temporarily halting the sending of messages to them, or changing available preferences. The common format for sending these commands is to send an email that contains simply the command followed by the name of the electronic mailing list the command pertains to. Examples: subscribe anylist or subscribe anylist John Doe. Some list servers also allow people to subscribe, unsubscribe, change preferences, etc. via a website.
Electronic mailing list servers can be set to forward messages to subscribers of a particular mailing list either individually as they are received by the list server or in digest form in which all messages received on a particular day by the list server are combined into one email that is sent once per day to subscribers. Some mailing lists allow individual subscribers to decide how they prefer to receive messages from the list server (individual or digest).

Two different types of mailing lists:
1. One type of electronic mailing list is an announcement list, which is used primarily as a one-way conduit of information and can only be "posted to" by selected people. This may also be referred to by the term newsletter. Newsletter and promotional emailing lists are employed in various sectors as parts of direct marketing campaigns.
2. A discussion list, in which any subscriber may post. On a discussion list, a subscriber uses the mailing list to send messages to all the other subscribers, who may answer in similar fashion. Thus, actual discussion and information exchanges can happen. Mailing lists of this type are usually topic-oriented (for example, politics, scientific discussion, joke contests), and the topic can range from extremely narrow to "whatever you think could interest us". In this they are similar to Usenet newsgroups, and share the same aversion to off-topic messages. The term discussion group encompasses both these types of lists and newsgroups.
On both discussion lists and newsletter lists precautions are taken to avoid spamming. Discussion lists often require every message to be approved by a moderator before being sent to the rest of the subscribers.The emails sent by whitelisted companies are not blocked by Spam Filters, which can often reroute these legitimate, non-spam emails.
Some mailing lists are open to anyone who wants to join them, while others require an approval from the list owner before one can join. Joining a mailing list is called "subscribing" and leaving a list is called "unsubscribing".

Mail Exploders, Lists, and Forwarders
It is a program that can forward copies of a message to the users in different domains.
The exploder uses a database to determine how to handle a message. Commonly called a mailing list, each entry in the database is a set of e-mail addresses. Furthermore, each entry in the database is assigned its own e-mail address(reflector address).
Mailing list Contents

friends joe@foobar.com, jill@bar.gov, tim@stateU.edu,
mary@acollege.edu
customers george@xyz.com, VP_marketing@news.com
Vball-interest hank@noexist.com, linda_s_smith@there.com,
john_Q_public@foobar.com



E-mail Gateways
Although a mail exploder can operate on any computer, forwarding an e-mail message to a large mailing list can require significant processing time. Thus, many organizations do not permit exploders or large mailing lists on conventional computers. Instead, the organization selects a smaall set of computers to run exploders and frowarders and froward e-mail. Thus a computer dedicated to the task of forwarding e-mail is often called a e-mail-gateway, or e-mail relay.


Chat Rooms
Internet relay chat(IRC)
Internet Relay Chat (IRC) is a form of real-time Internet chat or synchronous conferencing. It is mainly designed for group communication in discussion forums called channels, but also allows one-to-one communication via private message, as well as chat and data transfers via Direct Client-to-Client.
IRC was created by Jarkko Oikarinen in late August 1988 to replace a program called MUT (MultiUser talk). Oikarinen found inspiration in a chat system known as Bitnet Relay, which operated on the BITNET
Technical information
IRC is an open protocol that uses TCP and optionally TLS(transport layer security). An IRC server can connect to other IRC servers to expand the IRC network. Users access IRC networks by connecting a client to a server. There are many client and server implementations, such as mIRC and the Bahamut IRCd, respectively. Most IRC servers do not require users to log in, but a user will have to set a nickname before being connected.
IRC was originally a plain text protocol , which on request was assigned port 194/TCP by IANA(Internet Assigned Numbers Authority). However, the de facto has always been to run IRC on 6667/TCP and nearby port numbers (for example TCP ports 6112-6119) to avoid having to run the IRCd software with root privileges.
Commands and replies
IRC is based on a line-based structure with the client sending single-line messages to the server, receiving replies to those messages and receiving copies of some messages sent by other clients. In most clients users can enter commands by prefixing them with /. Depending on the command, these may either be handled entirely by the client, or - generally for commands the client does not recognize - passed directly to the server, possibly with some modification.
Due to the nature of the protocol, it is impossible for automated systems to pair a sent command with its reply.
Channels
The basic means of communication in an established IRC session is a channel. Channels in a server can be displayed using the command /list [#string] [-min #] [-max #] that lists all currently available channels, optionally filtering for parameters (#string for the entire or part of the name, with wildcards, and #min / #max for number of users in the channel).
Users can join to a channel using the command /join #channelname and send messages to it, which are relayed to all other users on the same channel.
Channels that are available across an entire IRC network are prepended with a ' # ', while those local to a server use '&'. Other non-standard and less common channel types include '+' channels — 'modeless' channels without operators, and '!' channels, a form of timestamped channel on normally non-timestamped networks.
Challenges
Issues in the original design of IRC were the amount of shared state data being a limitation on its scalability, the absence of unique user identifications leading to the nickname collision problem, lack of protection from netsplits by means of cyclic routing, the trade-off in scalability for the sake of real-time user presence information, protocol weaknesses providing a platform for abuse, no transparent and optimizable message passing, no encryption. Some of these issues have been addressed in Modern IRC.
· Attacks
Because IRC connections are usually unencrypted and typically span long time periods, they are an attractive target for malicious crackers. Because of this, careful security policy is necessary to ensure that an IRC network is not susceptible to an attack such as an IRC takeover war. IRC networks may also k-line or g-line users or networks that have a harming effect.
A small number of IRC servers support SSL connections for security purposes. This helps stop the use of packet sniffer programs to obtain the passwords of IRC users, but has little use beyond this scope due to the public nature of IRC channels. SSL connections require both client and server support (which may require the user to install SSL binaries and IRC client specific patches or modules on their computers).
IRC served as an early laboratory for many kinds of Internet attacks, such as using fake ICMP unreachable messages to break TCP-based IRC connections (nuking) to annoy users or facilitate takeovers.
· Abuse prevention
One of the most contentious technical issues surrounding IRC implementations, which survives to this day, is the merit of "Nick/Channel Delay" vs. "Timestamp" protocols. Both methods exist to solve the problem of denial-of-service attacks, but take very different approaches.
The problem with the original IRC protocol as implemented was that when two servers split and rejoined, the two sides of the network would simply merge their channels. If a user could join on a "split" server, where a channel which existed on the other side of the network was empty, and gain operator status, they would become a channel operator of the "combined" channel after the netsplit ended; if a user took a nickname which existed on the other side of the network, the server would kill both users when rejoining (i.e., 'nick-collision').
This was often abused to "mass-kill" all users on a channel, thus creating "opless" channels where no operators were present to deal with abuse. Apart from causing problems within IRC, this encouraged people to conduct denial of service attacks against IRC servers in order to cause netsplits, which they would then abuse.
· Nick/channel delay
The nick/channel delay (abbreviated ND/CD) solution to this problem was very simple. After a user signed off and the nickname became available, or a channel ceased to exist because all its users left (as often happens during a netsplit), the server would not allow any user to use that nickname or join that channel, respectively, until a certain period of time (the delay) had passed. The idea behind this was that even if a netsplit occurred, it was useless to an abuser because they could not take the nickname or gain operator status on a channel, and thus no collision of a nickname or 'merging' of a channel could occur. To some extent, this inconvenienced legitimate users, who might be forced to briefly use a different name (appending an underscore was popular) after rejoining.
· Timestamping
The alternative, the timestamp or TS protocol, took a different approach. Every nickname and channel on the network was assigned a timestamp – the date and time when it was created. When a netsplit occurred, two users on each side were free to use the same nickname or channel, but when the two sides were joined, only one could survive. In the case of nicknames, the newer user, according to their TS, was killed; when a channel collided, the members (users on the channel) were merged, but the channel operators on the "losing" side of the split lost their channel operator status.
TS is a much more complicated protocol than ND/CD, both in design and implementation, and despite having gone through several revisions, some implementations still have problems with "desyncs" (where two servers on the same network disagree about the current state of the network), and allowing too much leniency in what was allowed by the 'losing' side. Under the original TS protocols, for example, there was no protection against users setting bans or other modes in the losing channel which would then be merged when the split rejoined, even though the users who had set those modes lost their channel operator status. Some modern TS-based IRC servers have also incorporated some form of ND and/or CD in addition to timestamping in an attempt to further curb abuse.
Most networks today use the timestamping approach. The timestamp versus ND/CD disagreements caused several servers to split away from EFnet and form the newer IRCnet. After the split, EFnet moved to a TS protocol, while IRCnet used ND/CD.
NetworksThere are thousands of running IRC networks in the world. They run various implementations of IRC servers, and are administered by various groups of IRC operators, but the protocol exposed to IRC users is very similar, and all IRC networks can be accessed by the same client software.


The term chat room, or chatroom, is primarily used by mass media to describe any form of synchronous conferencing, occasionally even asynchronous conferencing. The term can thus mean any technology ranging from real-time online chat over instant messaging and online forums to fully immersive graphical social environments
A chat room is a Web site, part of a Web site, or part of an online service such as America Online, that provides a venue for communities of users with a common interest to communicate in real time. Forums and discussion groups, in comparison, allow users to post messages but don't have the capacity for interactive messaging. Most chat rooms don't require users to have any special software; those that do, such as Internet Relay Chat (IRC) allow users to download it from the Internet.
Chat room users register for the chat room of their choice, choose a user name and password, and log into a particular room (most sites have multiple chat rooms). Inside the chat room, generally there is a list of the people currently online, who also are alerted that another person has entered the chat room. To chat, users type a message into a text box. The message is almost immediately visible in the larger communal message area and other users respond. Users can enter chat rooms and read messages without sending any, a practice known as lurking.
Because chat room messages are spontaneous and instantly visible, there is a potential for abuse, which may or may not be intentional. Site hosts typically post a frequently asked questions (FAQ) list to guide users to appropriate chat room behavior, such as introducing yourself when you enter a room, making it clear when you are directing a question or response to a specific user, and reporting disruptive users, for example. Disruptive users may verbally abuse other chatters, monopolize the conversation, or even just disable it by repeatedly typing the same word or phrase into the conversation, a practice (much frowned upon) known as scrolling.
Chat rooms can be found that focus on virtually any aspect of human endeavor or interest: there are current communities based on classic movies, Irish ancestry, baton twirling, and psychic readings, for example. Various sites, such as Yahoo, provide a directory of chat sites. Others, such as MSN Web Communities, guide users through the steps required to create their own chat room.
Text-based chat:
Online chat is a way of communicating by sending text messages to people in the same chat-room in real-time. Some chat rooms such as Yahoo! use both text and voice simultaneously. The oldest form of true chat rooms are the text-based variety. Talkomatic, developed on the PLATO System around 1974, has a strong claim to have been the prototype of the text-only chat room. The most popular of this kind is Internet Relay Chat (IRC). The popularity of these kinds of chat rooms has waned over the years, and IRC's popularity has rapidly given way to instant messaging. Also a notable number of people were introduced to chat rooms from AOL and web chat sites.
There are also graphical user interface (GUI) text-based chat rooms which allow users to select an identifying icon and modify the look of their chat environment.

Graphical multi-user environments:
Visual chat rooms add graphics to the chat experience, in either 2D or 3D (employing virtual reality technology). These are characterized by using a graphic representation of the user (avatar) that can be moved about a graphic background or in a graphic environment. These virtual worlds are capable of incorporating elements such as games (in particular massively multiplayer online games) and educational material most often developed by individual site owners, who in general are simply more advanced users of the systems. The most popular environments also allow users to create or build their own spaces.
Some visual chat rooms also incorporate audio and video communications, so that users may actually see and hear each other. However, some find these types of environments cumbersome to use and actually an impediment to chatting.
Chat room activities:
The primary use of a chat room is to share information via text with a group of other users. New technology has enabled the use of file sharing and webcams to be included in some programs and almost all Internet chat or messaging services allow users to display or send to each other photos of themselves.
Games are also often played in chat rooms. Historic examples are initgame or Hunt the Wumpus on IRC.
Rules of behavior:
Chat rooms usually have stringent rules that they require users to follow in order to maintain integrity and safety for their users. Particularly in rooms for children, rules usually do not allow users to use offensive language, or to promote hate mail, violence and other negative issues. Also chat rooms often do not allow advertising in their rooms or flooding, which is continually filling the screen with repetitive text. Typing with caps lock on is usually considered shouting and is discouraged.[1]
Sometimes chat room venues are moderated either by limiting who is allowed to speak (not common), or by having moderation volunteers patrol the venue watching for disruptive or otherwise undesirable behaviour.
Yet, most commonly used chat rooms are not moderated and users may type what they personally choose to send.