How SMTP Works

LAN

Internet

LAN

with e-mail client software

Client computer

Server computer with

e-mail server software

SMTP packet

IMAP or

POP packet

(“message transfer agent”)

an e-mail message is sent as an SMTP packet to the local mail server

reads the packet’s destination address and sends it over the Internet to the receiver’s mail server.

stores the message in the receiver’s mail box

contacts the mail server which then downloads the message

(“user agent”)

Client computer