SMTP

Simple Mail Transfer Protocol or SMTP, is a common method of sending mail across the internet. The messages are transferred to a remote server using various procedures and responses between a client and a server. Both a user’s MUA (Mail User Agent) and a server’s MTA (Mail Transport Agent) may act as an SMTP client. An MUA recognizes an outgoing SMTP server because of how it is configured. An MTP is able to specify which SMTP server it needs to connect to by referring to DNS records for a recipient’s domain name. SMTP is often referred to as a push protocol that does not permit a user to automatically retrieve emails from a remote server at will. This is because the messages are normally deleted after being downloaded onto a hard drive. In order to achieve this, a more extendable mail client such as POP3 or IMAP must be used.