Simple Mail Transfer Protocol (SMTP)
SMTP is the protocol that email servers use to forward messages across a TCP/IP network. The client computer that initiates an email message also uses SMTP to send that message to a local server for delivery.
A user never has to speak SMTP. The SMTP communication process goes on behind the scenes. However, it is occasionally important to know a little about SMTP to interpret error messages for undelivered mail. Also, programs and scripts sometimes access SMTP directly to send email warnings and alerts to network personnel.
Like other TCP/IP application services, SMTP communicates with the network through the TCP/IP protocol stack. The duties of the email application are kept simple because the application ...
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