Simple Mail Transfer Protocol (SMTP)

Email (electronic mail) being sent over the internet utilizes SMTP as the standard means of transmission over Internet Protocol (IP) networks. The process in which an email is transmitted using the simple mail transfer protocol is as follows:

Email is submitted by a mail client
Mail server receives email
Mail server delivers email to mail transfer agent
Mail transfer agent locates target host
DNS is used to look up mail exchanger record
Target host is acquired and the mail transfer agent connects as an SMTP client
Mail exchanger record target accepts incoming email, transfers to mail delivery agent