Simple Mail Transfer Protocol (SMTP) is a web-based protocol for transmitting emails between servers. Initiated in 1982, it was last upgraded in 2008 – which has been sought across PC users since inception. No doubt, you can come across several email systems, however, majority of them rely on SMTP to send mails from one server to another. It is interesting to note that messages sent through Simple Mail Transfer Protocol can be eventually restored with the support of an email client using either POP or IMAP. Besides, SMTP is usually employed to deliver messages from a mail client to a mail server.