Simple Mail Transfer Protocol
Email from an E-mail client are sent to server using SMTP. SMTP (Simple Mail Transfer Protocol) is used for transferring email from an email client to server, and one mail server to another mail server. Its specifies how mail system work together and the formate of the control message they used to exchange and transfer mails. SMTP is not dependent on any particular transmission subsystem. This protocol makes the connection between the sender’s server and the recipient and they then transfer message.
How SMTP Work.
Working of Simple Mail Transfer Protocol is based on the model of combination , which is a result of user mail request. In this communication a two-way transmission channel established between the sender SMTP and a receiver SMTP. To provide the ending and receiving capability between the server and destination host, the SMTP server must be supplied with then name of the destination host as well as the name of the destination mailbox. The mailbox name identifies the strong space which set in a computer to receive an email and is the first part of the Email address. SMTP commands are generated by the sender SMTP and sent to the receiver SMTP. The server SMTP replies to the sender SMTP in response to those commands.
After establishing the transmission channel, the SMTP sender sends a mail command, signifying the sender Email. If the SMTP receiver accepts Mail command, It respond with an OK reply, of The SMTP sender, Sends a RCPT command identifying recipient of the mail. If the SMTP receiver accepts mail for the recipient then respond with OK. If not, its respond with reject. The SMTP Sender can also talk to several recipients at the same time.
The SMTP provides mechanism for the transmission of the Mail from the sending host to the receiving host. when the two host are connected to the same transport service. When the source and destination hosts are connected to the same transport service. Then they are connected via one or more relay SMTP-Servers. Then Relay SMTP server act as forwarders. They will forward the message from the Source to destination.