What is Simple Mail Transfer Protocol (SMTP)?
Simple Mail Transfer Protocol (SMTP) is a protocol used for sending e-mail messages between servers. It is mostly used to send messages from a mail client such as Microsoft Outlook to a mail server. Most of the e-mail systems that send mails over the Internet use SMTP to send messages from one server to another. Due to its limitations in queuing messages at the receiving end, it is generally used with either the POP3 or IMAP protocol, which enables a user to save and download messages from the server.
