How e-ink works.

In charge

The topic of this thesis is "Organization and functioning of E-mail in computer networks".

According to all the "rules" and "concepts", it is e-mail that should be placed in the first place in the list of Internet services. After all, it was the first to be born - simultaneously with the birth of the network itself - and for more than thirty years it was the main network "highlight" ... It is likely that in five years every inhabitant of the developed countries of the world will have their own e-mail address.

You can put into the "electronic envelope": photos, electronic copies of messages, files, programs, a copy of an electronic drawing and even a sound fragment. There are no restrictions on the type of information, except for the “weight” of the attachment. The maximum allowable message size depends on the "size" of the user's mailbox, that is, on the amount of disk space allocated by the provider for storing mail.

As a rule, the size of the mailbox is set by the email service, the size varies from 20 to 1024 MB for free, but for reasons of common sense and net etiquette, the size of a text message should not exceed one megabyte.

The main objects that make up an email system are special computers called mail servers and client computers that serve physical clients. The necessary components of this system are special programs and protocols.

E-mail, like regular mail, works with a system of electronic "post offices" - mail servers that forward letters over global networks. They interact using mail protocols that provide forwarding and recognition of information transmitted on the network.

Computers - mail server clients serve e-mail users. Everyone gets their mailing address and their "mailbox" on this computer, i.e. memory area, as well as a password to access it.

E-mail provides for the rapid transfer of messages from one point of the network to another, but is a typical type of delayed response service. You can send and receive messages by this mail at any time of the day or night.

An important advantage of e-mail is that the remoteness of the addressee practically does not play any role in terms of not only the speed of delivery, but also its cost.

The relevance of research. E-mail is constantly evolving and improving, which leads to more convenient use of it. Today, e-mail makes it possible to organize private correspondence between Internet users, and is also a modern means of transmitting information.

An Internet-accessible e-mail box is what most ISPs offer. By opening an account with one of them, the user, within the framework of a single package of services, gets access to a Web-based e-mail service operating under the POP3 or IMAP protocols.

The purpose of this final qualified work:

consider the general characteristics and technology of the functioning of e-mail;

installation of a mail server at the enterprise.

To achieve this goal, it is necessary to solve the following tasks:

Consider the basic concepts of e-mail: spam, encryption;

Describe the principle of e-mail;

Review the mailing format and email protocols.

Chapter 1. General characteristics of e-mail

Basic email concepts

The word mail (from the Latin "posita" - station) at first meant only a postal station, and then people delivering correspondence and related to this service.

E-mail (eng. E-mail or email, short for electronic mail) is a method of transmitting information in computer networks, widely used on the Internet 1 . A typical service of delayed reading (off-line). The user, as a rule, sends a message in the form of plain text, the addressee receives it on his computer after some, possibly quite a long period of time, and reads the received message when it is convenient for him.

There are two ways to work with email:

using the web interface of the mail server;

using a special program - an e-mail client, for example, Outlook Express, Netscape Navigator, MS Intenet Mail, THE BAT, Eudora MAIL, WinPmail and much more.

Mail client - a program that provides an interface for working with the mail system. This is where messages are composed, edited and working with addresses (address book function). This program must be (be installed) on the user's computer.

Let's compare the characteristics of popular email programs:

Outlook Express is a program that shows server names, usernames and passwords for mail and news accounts stored in Outlook Express, as well as passwords that allow you to identify the user (identity passwords).

The start page of the mail client is very competently implemented, on which links are placed to all the main actions with it, as well as one arbitrary useful tip related to mastering the program. Outlook Express has an extensive Russian-language help that describes in detail all the nuances of working with the program. With a little bit of irony, I would like to note that the production of high-quality "references" is a strong point of Microsoft Corporation. Simply, we are not accustomed to appreciate it.

Speed:

Maximum integration with the operating system allows Outlook Express to run at supersonic speeds. One of the advantages of the mail client is the high speed of mail processing, regardless of the amount of information transmitted.

The entire interface of the mail client is based on standard Windows libraries, which provides excellent window rendering speed.

Post editor:

Creating messages in HTML format using Outlook Express is extremely inconvenient. You can't insert your own lines in the middle or end of a post because the vertical quoting bar is non-breaking. You have to compose your message exclusively above the quoted body of the original. The HTML code generated by the message editor is very bulky and many times larger than the text equivalent.

Functionality:

The capabilities of Outlook Express are a kind of standard that other developers start from in the hope of winning over the user with something more functional. Outlook Express has a standard set of features applicable to many email clients.

The mail client contains elements of integration with Windows Messenger, which allows you to synchronize the contact panels of both programs.

Third-party developers are on the alert, and through their efforts, you can extend the capabilities of Outlook Express. To date, many external message managers have been written that can check mail on the server, open headers, and then transfer control to the mail client. There are also programs that allow you to insert funny faces, which we call emoticons, into messages created in Outlook Express.

Mail sorting:

Sorting mail is limited to filters, according to which we can perform any action based on strictly defined conditions. You can create additional folders where you can later place messages that meet specific criteria.

Security:

Outlook Express is the most vulnerable email client in the world. The use of the Trident engine, as well as the absence of any tools to "neutralize" it, put an end to your peace of mind. Statistics show that Outlook Express is the main "explorer" of viruses on your computer. Virus infections through the browser are much less common.

Outlook Express is a very simple and fast tool for unassuming users. Poor virus protection is the main problem of Outlook Express, which has to be solved with the help of powerful anti-virus protection.

Development:

Interface The Bat! is an evolutionary development of technologies laid down in the nineties of the last century. In recent years, the mail client has acquired new features in the form of beautiful icons on the toolbar, and the panels themselves can be moved with the mouse within the entire working window of the program (Appendix 9).

But the tendency to increase the number of menu items of the same type remained unchanged, which regularly happens from version to version. Of course, for a user who has been working with a bat since the very first versions, such a gradual increase in the complexity of the interface seems almost imperceptible, but for those who want to switch to a Moldovan program for the first time, this can become a serious obstacle.

The Russian-language terminology used in the program is very different from the usual standards.

The lack of a start page can also complicate the first steps. Help in English.

Speed:

Despite the maximum distance from the environment of the operating system, The Bat! shows good speed. The email client shows an average first load time and renders messages with HTML-formatted mailing lists rather quickly. Being multithreaded, The Bat! allows you to receive and send letters at the same time, which increases the speed of interaction with servers. The modest system requirements allow the bat to run fast even on outdated workstations.

Post editor:

Powerful template management tools give you the flexibility to customize salutations and signatures to suit your preferences. The Bat! - the only e-mail client from the "top ten", in which you can apply alignment "by width" in text (!) mode. In addition, if you mixed up the case of letters, then this can be quickly corrected using a special group of functions. Quick templates allow you to automate the input of frequently used phrases. Support for "slogans" adds additional charm and elements of humor to personal correspondence.

Serious problems begin when you switch to the mode of creating messages in HTML format. You cannot break the quote and are forced to enter your entire text above/below the original message. Changing the format from HTML to plain text doubles the number of lines in the message. Each informative line will be followed by another empty one.

The created message in HTML format exceeds the size of a similar text message by more than 4 times (Appendix 10).

Functionality:

The Bat! is focused on the serious user, for which a lot of service functions are provided. Bat has an excellent mail manager that allows you to filter out unnecessary messages before transferring them to local media. The process of exchanging messages with the server is carefully visualized, you can see a clear indicator showing the progress of the work. Having a built-in SmartBat scheduler allows Bat to compete with Outlook in a corporate environment. It is very useful to have a work log, which stores information about all network operations.

The Bat! able to export/import mail, working with many formats. Bat steadfastly withstands the import of thousands of mail databases from Outlook, Outlook Express and all the mailers from the Mozilla zoo. The full list of email clients from which you can import the database consists of eight items.

The Bat! has the ability to work as a server in the local network.

You can change the password on the server directly from the mail client, organize a local chat using e-mail messages, encrypt letters, and manually set the type of network connection for the mail client to work. networks CLASSIFICATION NETWORKS BY STANDARDS ORGANIZATIONS There are many standards that provide functioning networks. ... computer communication via satellite or telephone. Electronic mail- the most popular service networks ...

Introduction

1. Email. General characteristics

1.1 Email standards

1.2 Email programs

1.3 Registering mailboxes

1.4 E-mail etiquette

2. Technology of functioning of e-mail

2.1 Receiving and sending messages

2.2 Address book

2.3 Working with attachments

2.4 Email security

Conclusion

Glossary

List of used literature

Applications

Introduction

The Internet is the last and most important achievement of the 20th century. It changed the world and affected the life of every person on the planet, no matter how far he was from computers and computer networks. In terms of its impact on society, the Internet is comparable to telephone communications, television, radio and print media combined. However, this is not surprising, because he has already absorbed all the achievements of mankind both in the information sphere and in the communication industry.

The possibilities of the Internet and the needs of humanity go hand in hand. Communications and software are changing, and so are the possibilities on the Internet.

Among the basic user technologies, a special place is occupied by e-mail, which allows you to send a message in a matter of minutes, containing both text and sound, and graphic, and program files. By e-mail, using the UseNet network, you can receive the latest world news, read messages in teleconferences, and make business transactions.

Email is similar to regular mail in many ways. With its help, a letter - a text provided with a standard header (envelope) - is delivered to the specified address, which determines the location of the machine and the name of the addressee, and is placed in a file called the addressee's mailbox, so that the addressee can get it and read it at a convenient time . At the same time, there is an agreement between mail programs on different machines on how to write the address so that everyone understands it.

For each subscriber on one of the network computers, a memory area is allocated - an electronic mailbox. Access to this memory area is carried out at the address that is reported to the subscriber, and the password that the subscriber invents himself. The password is known only to the subscriber and the network computer. Having become a subscriber of a computer network and having received the address of his mailbox, the user can inform his friends and acquaintances. Each e-mail subscriber can send a letter through his computer and modem to any other subscriber, indicating his postal address in the message

E-mail (E-mail) - one of the first Internet services. Over the years, it has not lost popularity and remains in demand by the vast majority of users. Its main advantage is that email is the optimal method of non-intrusive communication. The message does not reach as quickly as on instant communication systems, but the correspondent can read it at a convenient time for him and respond when he has the opportunity.

In other words, e-mail is the best way to communicate if it's inconvenient to interrupt people from urgent matters (as opposed to a phone call, which somehow has to be answered immediately).

An important advantage of e-mail is that the remoteness of the addressee practically does not play any role in terms of not only the speed of delivery, but also its cost, because only the time of connection to the Internet is paid by the provider.

Modern people like to communicate, and modern technology provides them with such an opportunity in different circumstances and at different distances. A person becomes more and more dependent on the volume of information flows, so the urgency of the problem of developing communications is becoming more and more intense.

The purpose of the study is to highlight such points as the purpose and principles of the functioning of e-mail.

To achieve this goal, it is necessary to solve the following tasks: consider e-mail standards, basic mail programs, mailbox registration technology, give a comparative description of mail servers, describe the process of preparing, sending and receiving messages. And it is also necessary to consecrate issues such as etiquette and email security.

1. Email. General characteristics

1.1 Email Standards

E-mail - (eng. E-mail or email, short for electronic mail), a method of transmitting information in computer networks, is widely used on the Internet. The main feature of e-mail is that information is not sent directly to the recipient, but through an intermediate link - an electronic mailbox, which is a place on the server where the message is stored until the recipient requests it. Access to the mail server can be provided both through mail programs and through the web interface.

E-mail works in a similar way. It uses two types of servers. One server sends outgoing mail regardless of its origin - it uses the Simple Mail Transfer Protocol (SMTP). Another server receives incoming mail and makes sure that it gets to the right recipients. This protocol is called POP3 (Post Office Protocol).

SMTP - (eng. Simple Mail Transfer Protocol, a simple mail transfer protocol) is a network protocol designed to transfer e-mail in TCP / IP networks. The protocol was designed to transmit only ASCII text, in addition, the first specifications required the most significant bit of each transmitted byte to be set to zero. This does not allow sending text in national languages, as well as sending binary files. To remove this limitation, the MIME standard was developed, which describes a way to convert binary files to text. Currently, most servers support 8BITMIME, which allows you to send binary files.

ESMTP - (eng. Extended SMTP, a scalable extension of the SMTP protocol). Currently, "SMTP protocol" usually refers to SMTP and its extensions. When a connection is established, the server advertises the set of supported extensions. The corresponding extensions can be used by the client during work.

POP3 - (eng. Post Office Protocol Version 3, Post Office Protocol, version 3), a network protocol used to receive e-mail messages from a server. Usually used in conjunction with the SMTP protocol. The POP3 protocol provides for 3 session states: authorization (the client passes the authentication procedure), transaction (the client receives information about the state of the mailbox, receives and deletes mail), update (the server deletes the selected letters and closes the connection).

IMAP (Internet Mail Access Protocol) has also been developed to receive mail. It implements additional functions, in particular, messages are stored on the server and downloaded to a computer for viewing only. The messages are managed by the server itself. This protocol is convenient if you need to receive mail from the server on different computers.

IMAP - (eng. Internet Message Access Protocol), an application-level Internet protocol for accessing e-mail. IMAP provides the user with rich options for working with mailboxes located on a central server. A mail program that uses this protocol accesses the mail storage on the server as if the mail was on the recipient's computer.

1.2 Email programs

Of the many e-mail programs that run under Windows in SMTP/POP3 standards, we can name, for example:

· Outlook Express, supplied as part of the Windows operating system, starting from version 950SR 2.5 and together with the Internet Explorer browser, starting from version 4.0;

Microsoft Outlook office application (computer program - organizer with mail client functions);

e-mail components as part of browser programs;

· The Bat of the Moldavian company RIT Research Labs;

· Mail, HotMail, Hotbox and other free mail servers on the Internet;

Opera Mail (M2);

· Mozilla Mail of the Mozilla Foundation, new name Sea Monkey;

· Qualcornm's Eudora Mail (one of the first e-mail programs) and many others.

Almost all of these programs perform the following functions:

preparation of the text of the message;

sending and receiving correspondence;

Reading and saving correspondence;

Deleting messages

Entering the address(es) of the correspondent;

· inclusion of attachments in created messages - text, graphic files, audio and video files;

inserting an electronic signature or business card of the sender into the message;

maintaining an electronic address book;

commenting and forwarding the received correspondence to other subscribers;

search for the necessary correspondence according to the specified criteria;

import (receiving and converting text into the desired format) of other files;

Periodic checking of new mail;

· modem control to establish an IP connection;

Sorting messages into folders.

Switching from one mail program to another is possible, but not always convenient. The easiest way is to change Outlook Express to any other program, since the format in which Outlook Express stores data is well known and it is easy to transfer the accumulated correspondence to another program.

The principles of working with e-mail are practically independent of the program. Most users get started with email using Outlook Express or one of the Web-mail systems. In the future, more effective means are selected. An example of the implementation of e-mail on the Internet (Appendix 1).

1.3 Registering mailboxes

Any e-mail user must be registered with one of the Internet mail servers. The mail server is organized on the Internet host. This is usually the provider node. By registering on the mail server (through your provider), you receive an email address, and your mailbox is created on the server, in which incoming mail will accumulate.

Hello my reader!

With the advent of the Internet in every home, we gradually began to forget about the letters, postcards and invitations that we used to send by mail and receive from the hands of couriers or postmen.

In fact, e-mail is an analogue of an ordinary postal service. But we should not wait for several days, or even weeks, until the letter reaches. Everything happens instantly.

If you don't know how to use e-mail and in general how to create your own mailer, then I will tell you.

What is a postman?

A mailbox, or, as people say, a mailer, mail or “soap” is a repository of all outgoing and incoming messages. To use it, you first need to register your account.

This is done very simply. Enter “email” into the search engine and you will see a list of all the most popular mail services.

The registration structure is similar to each other:

1. enter the desired login
2. come up with a password.
3. fill in all the specified fields with registration data (name, date of birth, phone number, address, etc.)
4. entering the code from the picture (this is how the system checks if you are a robot).

As for passwords, this is a separate issue. You must be able to create complex passwords and store them in a safe place. To understand this, I recommend reading two articles:

The most popular mailer in Runet is mail from Yandex. This mail service is distinguished by its simplicity and easy navigation. For beginners, this is what you need!

The global corporation Google also did not bypass mail services. They have huge popularity all over the world. This allows users to send messages anywhere in the world, be it America, Africa or Asia. But, despite its versatility, many users complain about the intricacy of managing the Google mailer.

In addition to these two huge services, there are thousands of other email servers that also find their admirers on the Internet.

If you want to ask: “which one is better?”, then hardly anyone can answer this question for you. Yandex.Mail, Gmail, Rambler, Freemail, E-mail, etc., they all have their pros and cons, you just need to get used to the interface.

MicroSoft Corporation also has its own mail server - OutLook. It is popular because the Windows operating system has a client installed that will make it easier for you to work with emails. Register on the site, and then enter the data into the program and you're done, now you can view messages on your computer without using. And the client navigation is much more convenient than in the browser version of mailers.

What else do you need to know about email?

Firstly, it's not just a service for sending emails. You can send photos, videos and a variety of documents, programs, etc.

Secondly, almost every e-mail server has , which allow you to store large amounts of information and have access to them at any time via the Internet. In the cloud, your files won't be affected if your computer crashes or your hard drive crashes. This is a very useful option for most office workers who work with securities and for accountants.

Thirdly, you need to know that there are, as the people called them, "conflict" mailers. This term means the impossibility of sending a message from the mailbox of one service to another. Most often, these are servers of competing services.

The email account is protected by a password that the user chooses.

There are several ways to create an email account:
1. If you have an account with an Internet Service Provider (ISP), you may also have a POP (Mail Protocol) account.
2. You can get a web-based email account from organizations providing free email services such as Hotmail, Yahoo, Mail, Rambler, Google, and others.

Web-based email is typically implemented using a protocol called IMAP.

The IMAP protocol is similar to POP and is also used to download mail. Unlike POP, this protocol downloads headers and maintains a constant connection with the server.

It is not as stable as POP, but it has two advantages:
Due to the fact that each message is not downloaded, it is possible to manage a large number of letters.
You can use IMAP to delete certain messages directly from the server.

You can get yourself as many mailing addresses as your memory allows, that is, if you manage to remember all these addresses and passwords. But if you need to have a large number of email addresses, for example, to send information, then there are special programs for this, as well as for storing all logins and passwords hidden under one password.

When sending an e-mail message, the SMTP protocol is used. This is the language in which your computer communicates with another machine when sending email.

When receiving e-mail, the mail client program also uses POP or Internet Message Access Protocol (IMAP), depending on the server from which it receives mail.

Let's look first at how an e-mail message finds its way to its recipient located elsewhere in the world.

The Internet mail system, in fact, is a combination of a client-server and server-server system, in which a whole group of agents work invisibly. The email message is composed using client programs such as Microsoft Outlook Express, Netscape Messenger, The Bat, KMail, Novell GroupWise, Lotus Notes, and others.

The e-mailman delivers it to the designated post office, i.e. to the outgoing mail server that you have chosen. This server may need to communicate with another mail server if the recipient is outside its area of ​​responsibility. Upon receiving an e-mail message, the mail server at the receiving end asks another program running on the server to place the e-mail in the recipient's mailbox.

The recipient's email client actually receives the email message from the mailbox on the incoming mail server.

The mail client program is called the Mail User Agent (MUA), and the mail server is called the Mail Transfer Agent (MTA). MUA deals with both delivery and receipt of mail messages.

It is not the MTA that actually places e-mail messages in the recipient's mailbox. This is handled by another small program called the Mail Delivery Agent (MDA).

As we can see, various software agents are involved in e-mail processing. Like humans, in order to get their work done, they must use a common language, which is the protocol.

At present, the transmission of letters by e-mail is very widespread among all age groups. Probably, many did not even think about what exactly helps them send letters to other people.

Email is one of the ways to communicate through the worldwide web. Fairly fast. There are other forms for exchanging information: forums, chat rooms, ICQ-phones. But e-mail involves a larger amount of writing and a certain style of presentation. It is mainly used for business correspondence, but it is also good for personal.

letter by e-mail sent in much the same way as by regular mail, only all the tools (pen, paper, post office) are in the computer and the Internet. The sheet here can be either a regular text document, such as Microsoft Word, or a page in the e-mail itself. Before deciding what to use, the sender determines how long his letter will be. If it is large, it is better to attach it as a separate file, if not, write it directly in the body of the letter - a window that will open in the mail. You can attach a file to a letter using a paperclip, next to which it says “Attach” or “Attach”. In the special field "To" fill in the address of the person to whom you are going to send the letter. For example, [email protected](fictitious address for illustration). Such a record means that the mail server with the Internet address ugmk-telecom.ru hosts the drugu e-mail box. The return address is usually filled in automatically, because. the mail program is configured to process your mailbox. Then you just need to click "Send", and periodically check the mail, waiting for a response from a friend.

Let's pay attention to a few tricks , which you should keep in mind to facilitate your work with sending or in the future when searching for letters. Firstly , always indicate clearly the subject of the letter: in case the correspondence turns out to be important, and you need to return to it more than once, you can easily find messages in the Inbox folder by the subject of the letter. Secondly , a situation may arise when you need to specify a specific person for whom the letter is intended. For example, in cases where a group of people uses mail. To do this, you can specify his name directly in the address line, but then enclose the address itself in angle brackets: I. I. Ivanov . Thirdly , if you need to reply to a letter, it is not necessary to close the letter you are reading and write a new one. All you have to do is click "Reply". Then you do not have to re-enter the recipient's address. Finally , in the "Address Book" you can collect the addresses of mailboxes to which you often send letters. Further, simply choosing names from the list, it will be easier for you to fill in the addressee field in the letter.

All work with the letter takes place in mail client are programs designed to work with e-mail. With their help, you can read, send mail, filter incoming correspondence, sort both incoming and outgoing letters, save drafts (written but not sent letters). Moreover, all these actions (except for receiving and sending) are performed on a local computer, without access to the Internet.

The most popular in Russia are two mail clients : MS Outlook Express and The Bat!. Outlook Express comes with any operating system from Microsoft. It does not require installation of additional programs and additional payment. The Bat! - a product of the Moldovan company RITLabs. Its popularity is due to the large number of opportunities provided.

Well, you finally figured out the capabilities of your email client, composed a letter, entered the address, determined the subject and sent it by e-mail. What happens to the message. Next, the server for sending mail messages SMTP (Simple Mail Transfer Protocol) server finds the address of the destination server and sends a letter there. If such a mail server does not exist, then it will return the letter back indicating the reasons why it could not deliver the mail. If the recipient's server is found, it already checks if it has the specified mailbox and places the letter there. It will lie until the user opens it.

The recipient of the letter looks into his mailbox. At this moment, everything that has been received in the mailbox since the last mail check is downloaded from the mail server to the computer (in the case of a mail client) or displayed on the mail server website page. And after a few seconds, he is able to read the email.