SMTP is a protocol for transmitting e-mail. Unlike standard POP3, this server is primarily focused on transmission, although it is possible to receive a letter at a specific address within the protocol. SMTP is widely used by most modern mail services.
SMTP functions
SMTP is implemented in modern TCP / IP networks. For the first time, information about the use of the protocol appeared back in 1982. Despite the fact that the SMTP server can also be used to receive messages, today most mail clients use it only for sending, preferring other technologies (for example, POP or IMAP) for receiving information. The protocol is one of the most popular and is used by the overwhelming majority of mail programs and servers.
The SMTP function is to check the correctness of the settings and parameters for sending a letter. This protocol is used to verify the settings of the user's computer trying to send messages, and then delivery is performed if all settings were made correctly. After that, the SMTP work does not end and the server waits for a message about successful data delivery. If the message cannot be delivered for some reason, an appropriate message is sent to the sender.
Configuring SMTP
Configuring SMTP consists in installing the necessary software and determining the server address used for sending. To send from the user side, you need to install a client program that can send letters and communicate with the SMTP server using the TCP / IP protocol. After that, the program is launched and configured to work with the service for sending and receiving mail by specifying the required settings. The user then tries to send a message. If the settings are correct, the letter will be delivered to the addressee.
Most modern email services already have servers configured to send messages. If you do not use third-party software for sending letters, you can send a letter without making additional settings on the service website where you have an account.
Modern SMTP server administrators require users to be authenticated before they can send their message. The user must first specify his username and password on the server, and only then proceed to sending. This protection is used to block the possibility of sending spam using simple SMTP protocols. Previously, the unique IP address of the sender was used for identification in the SMTP protocol.
