smtp (simple mail transport pr

Short for Simple Mail Transport Protocol. Used for sending, receiving e-mail but, because is simple is limited in ability to queue messages at receiving end, usually used with either POP3 or IMAP protocols which allow user to save messages in server mailbox, download them periodically from server. SMTP authentication requires client to log into mail server, allowing legitimate users access to service while denying service to unauthorized users, such as spammers.