Let’s create a test message in a certain encoding with an attached file.
Create, send and receive a message
1. Enter the [Message-Create] command.
In the Create message window, in the To: field, you must specify the recipient’s email address, for example: email@example.com
In the Copies: field, you can specify the addresses of the recipients of the message copy.
The Subject: field specifies the subject of the message, such as “Test Message”.
2. In the area reserved for the message, the text of the message is entered, for example, “Test message (coding K0I8-P)”.
The choice of the correct encoding of the Russian letters of the message is quite important. When using e-mail, Windows and K0I8-P encodings are most often used.
3. Select the encoding using the command [Format-Type of encoding-Cyrillic (К0И8-Р)].
You can insert files (text, graphics, sound, and so on) into the message.
4. To insert a file into a message, enter the [Insert-File Attachment…] command. In the Insert window that appears, you must select the required file, and it will be attached to the message.
5. Insert, for example, into the message the sound file Debussy-Moonlight.ggtp from the Media folder, which is located in the Windows folder. The name of the attached file will appear at the bottom of the message box.
If the message was created offline without an Internet connection, the message must be saved in the Outbox folder.
6. After finishing work on the message, click on the Send button, the message will be placed in the Outbox folder.
To send a message to a recipient, you must be connected to the Internet.
7. Click the Deliver Mail button. A connection will be made to the mail server, and all messages in the Outbox folder on the local computer will be delivered to the mail server. Messages sent at the same time will be moved to the Sent Items folder on the local computer.
The provider’s mail server will transfer messages to the Internet and after a while they will be delivered to the recipients’ mail servers. In this case, the test message will go to the mailbox firstname.lastname@example.org
To receive a message, the subscriber must connect to the Internet and perform the operation of delivering mail from the provider’s mail server to his local computer.
8. Click the Deliver Mail button. During the mail delivery process, messages stored in the mailbox on the mail server will be transferred to the recipient’s local computer and placed in the Inbox folder.
If you set an encoding that is different from the one used when creating the message, the message will be complete gibberish.
9. In this case, you need to select the encoding using the [Format-Encoding Type…] command.
If you have an email address , you can send and receive emails over the Internet. And not only text, but also pictures, photographs, documents.
There are many sites where you can create mail for free. There are two major “mail” sites. These are the yandex.ru site and the mail.ru site. On other sites, creating mail and working with e-mail is almost the same.
How and where to create mail
In fact, it is not so important on which site you have mail. Someone prefers Yandex-mail, someone prefers mail.ru, while others choose google mail or rambler.ru. And there are people who create mail on smaller sites. The principle of operation is the same for everyone. This is the same as the difference between mobile phones: in principle, they are all, in general, the same. You can buy the cheapest model, and still be able to perform the necessary operations – make a call, receive a call, send and receive an SMS message. But it is better, of course, when your mobile phone is reliable, modern and has additional functions: so that you can access the Internet from it, take a photo, and play your favorite melody. It’s the same story with email. Usually, the larger the site on which you created the mail, the better. This is because on such sites, mail is monitored and constantly improved.
The mail server, having received mail (from a local source or from another server), checks if there are specific rules for processing mail (rules can be based on a username, on a domain in an address, on the content of a letter, etc.), if no specific rules are found , then it is checked whether the mail domain is local to the server (that is, whether the server is the final recipient of the letter). If it is, then the letter is accepted for processing. If the mail domain is not local, then the mail routing procedure (which is the basis for transferring letters between different servers on the Internet) is applied.
Routing uses only the domain part of the destination address (that is, the part after the @ symbol). For the recipient domain, all MX records are looked up. They are sorted in descending order of priority. If the mail server address matches one of the hosts specified in the MX records, then all records with a priority lower than the host’s priority in the MX record (as well as the MX record of the host itself) are discarded, and delivery is made to the first responding host (nodes are tried in descending order of priority). If the MX record for the domain is not found, then some servers may try to deliver mail using the A record. If there is no record about the domain, then a whack is generated (message about the impossibility of delivery). This message is generated with an empty sender field, the “To” field specifies the sender of the original message. An empty sender field allows you to protect mail servers from endless circulation of error messages between servers – if the server finds that it cannot deliver a letter with an empty return address, then it destroys it.
If the network has different DNS servers (for example, external – on the Internet, and local – within its own limits), then it is possible that the “internal” DNS servers point to a server that is not available on the Internet as the highest priority recipient, where mail is redirected from the relay specified as the recipient node for the Internet. This division allows mail to be routed according to common rules between servers that do not have access to the Internet.
The mail system allows you to organize complex systems based on the forwarding of mail from one to many subscribers, these are:
Mailing lists – a letter from the same address with the same (or changing according to the template) content, sent to mailing list subscribers . Technically, it can be organized as sending multiple emails (used for template emails) or sending emails with multiple recipients (in TO, CC, BCC fields). To manage large mailing lists (more than 10-50 subscribers), specialized programs (for example, mailman) are used. A properly organized mailing list should control the return of letters (messages about the impossibility of delivering a letter) with the exclusion of unavailable recipients from the mailing list, allow subscribers to unsubscribe from mailing lists. Unwanted mailings are called spam and significantly complicate the functioning of mail systems.
Correspondence groups are a specialized type of mailing list in which a letter to the group address (a regular postal address processed by a specialized program) is sent to all members of the group. It is an analogue of news conferences, echo conferences. A properly configured mailing list should control cycles (two mailing robots subscribed to each other are able to create an endless loop of sending letters), limit the list of mailing list participants who have the right to post a message, and fulfill other mailing list requirements.
Mailing list managers are used to manage mailing lists . In addition to maintaining a list of addresses and sending a given message, they provide filtering of letters, the possibility of pre-moderation of letters before placing them in the mailing list, maintaining archives, managing subscription / unsubscribing, mailing digests (short content) instead of the entire mailing volume.
Examples of mailing management programs:
Spam is a type of mailing for the purpose of advertising (often unsolicited) a particular product or service, an analogue of paper advertising distributed free of charge in the mailboxes of residential buildings.
As e-mail grew in popularity, it (along with usenet newsgroups) began to be used to send out unsolicited promotional messages, similar to how brochures are dropped into traditional mailboxes. However, unlike the substantial cost of a paper mailing list, sending a significant amount (millions and billions) of messages costs virtually nothing to the sender. This led to a disproportionate increase in the number and size of advertising mailings (according to some data  , spam currently accounts for 70-90% of all email messages, that is, it exceeded the payload by 2-10 times).
To send spam, all possible technical tricks are currently actively used: open relays, remailers, proxy servers, free email servers (allowing automation of sending mail), botnets, fake messages about undeliverable.
With the tightening of the ban on advertising, the messages were divided into legitimate mailings (which the user usually subscribes to and from which he can refuse at any time) and illegitimate (actually called spam). To combat spam, various mechanisms have been developed (black lists of senders, gray lists that require the mail server to re-apply for sending, context filters). One of the consequences of the introduction of anti-spam tools was the possibility of a “false positive” decision regarding spam, that is, part of the letters that are not spam began to be marked as spam. In the case of an aggressive anti-spam policy (destruction of messages that appear to be spam automatically without notifying the sender/recipient), this leads to hard-to-detect problems with the passage of mail.
The following components are distinguished in the terminology of e-mail:
MTA (English Mail Transfer Agent – mail transfer agent) – is responsible for sending mail; most often this is a mail server, but, in principle, it can be implemented with sending mail through a smart host.
MDA (English Mail Delivery Agent – mail delivery agent) – is responsible for delivering mail to the end user.
MUA (eng. Mail user agent – mail user agent; in Russian notation, the term mail client was fixed) – a program that provides a user interface that displays received letters and provides the ability to respond, create, redirect letters.
MRA English Mail retrieve agent – a mail server that retrieves mail from another server using protocols designed for MDA. [eight]
In the case of using the web interface, MDA and MUA may be the same. In the case of using dedicated servers for storing user mail, all interaction between the user and the server can occur using protocols that do not fit into this scheme.
Mail servers usually act as MTAs and MDAs. Some mail servers (programs) perform the role of both MTA and MDA, some involve separation into two independent servers: MTA server and MDA server (at the same time, if different protocols are used to access the box – for example, POP3 and IMAP, – then MDA, in turn, can be implemented either as a single application, or as a set of applications, each of which is responsible for a separate protocol).
1. N. Ugrinovich “Computer science and information technologies” 2002
2. http://www.elektronnaya pochta.html