What Is Authenticated SMTP Submission?
SMTP, the Simple Mail Transport Protocol, is used to transfer mail from one mail server to another; it has also been used to submit mail from a user’s mail client to a mail server for delivery. Historically, all mail servers accepted mail for all addresses, even if the server did not provide service to that address, and forwarded the mail to the appropriate location. With an increasing volume of spam, this approach became untenable and mail server generally now only accept mail from (1) clients on their own IP networks or (2) for addresses that they serve. As a result, sending mail from a remote network with a local address to a remote user becomes problematic. For example, say you’re a cs.ualberta.ca user visiting cs.ubc.ca, and you want to send mail to cs.utoronto.ca: the cs.ualberta.ca outbound mail server will reject your mail since it’s not going to cs.ualberta.ca; you’d need to use cs.ubc.ca’s outbound mail server to send the mail instead. And each time you change your location,
