6.12. Simple Mail Transfer Protocol (SMTP)

Email had a to some degree rough begin on the Internet, with early email programs sharing couple of gauges with other email programs, especially in the treatment of appended binary data. The uplifting news is that the circumstance is presently determined, and all present email programming bolsters all the broadly acknowledged principles.

The Simple Mail Transfer Protocol (SMTP) is utilized to send and get email messages starting with one email server then onto the next. The SMTP protocol characterizes a discourse between a sending framework and an accepting framework.

A SMTP discourse begins when a sending framework associates with port 25 of an accepting framework. After the association is built up, the sending framework sends a HELO command, trailed by its location. The accepting framework recognizes the HELO command alongside its own particular location. The discourse then proceeds, with the sending framework issuing a command demonstrating that the framework needs to communicate something specific and distinguishing the beneficiary for whom the message is expected. On the off chance that the getting framework knows of the beneficiary, it recognizes the request, and afterward the sending framework transmits the body of the message alongside any attachments. At last, the association between the two frameworks is ended once the getting framework recognizes that it has gotten the whole message. Figure 6.12 outlines this procedure.

Figure 6.12. Part of an SMTP dialog between systems