SMTP is the protocol for transfer of e-mail. Unlike standard POP3, this server is focused mainly on transfer though there is an opportunity and receipts of the letter to a certain address within the protocol. SMTP is widely applied by the majority of modern mail services.
SMTP functions
SMTP is implemented in modern networks of the TCP/IP standard. For the first time information on use of the protocol appeared in 1982. In spite of the fact that the SMTP server can be used also for obtaining messages, today the majority of e-mail clients use it only for sending, preferring other technologies (for example, POP or IMAP) for reception of information. The protocol is one of the most popular and is used by overwhelming number of email clients and servers.
The SMTP function consists in validation of the indication of settings and parameters for sending the letter. Under this protocol there takes place verification of settings of the computer of the user trying to send messages and then delivery is made if all tunings were performed correctly. After that work of SMTP does not come to an end and the server waits for the message about successful delivery of data. If the message cannot be for some reason delivered, the corresponding message to the sender is sent.
SMTP setup
The SMTP setup consists in installation of the necessary software and definition of the address of the server used for sending. For sending from user side it is required to install the client program which is able to transfer letters and to contact the SMTP server under the TCP/IP protocol. After that the program is started and configured for work with service of sending and receiving mail by the indication of the necessary settings. Then the user tries to send the message. If setup is carried out truly, the letter will be delivered to the addressee.
Most modern services of e-mail already have the configured servers for sending messages. If you do not use the third-party software for sending letters, you will be able to send the letter without performing advanced settings on the website of service where you registered the account.
Modern administrators of SMTP servers demand from users of passing of authentication before they are able to send the message. The user needs to specify at first the login and the password on the server, and only then to pass to sending. This protection is used for the blocking of a possibility of spam sending using simple SMTP protocols. Earlier for identification in the SMTP protocol the unique IP address of the sender was used.