Web Hosting Glossary -
Sender Policy Framework (SPF)

Sender Policy Framework (SPF)
Sender Policy Framework (SPF) is an extension to the Simple Mail Transfer Protocol (SMTP). SPF allows to identify and reject forged addresses in the SMTP MAIL FROM (Return-Path), a typical nuisance in e-mail spam. SPF is defined in the SPF Classic specification.

SPF fights return-path address forgery and makes it easier to identify spoofs.
Domain owners identify sending mail servers in DNS.
SMTP receivers verify the envelope sender address against this information, and can distinguish authentic messages from forgeries before any message data is transmitted.

Why Email Forgery?
All spam has a cost for the people who get it, but forged spam has a much bigger cost for the people whose addresses get forged into the messages. ISPs can close their accounts. They receive nasty emails from people who received the forged spam. Their mailbox gets clogged up with bounce messages. And it happens to a lot of people, people who would never spam, every day.

Furthermore, how do you complain about spam, track down the spammer, if it's easy for them to hide their identity? Even in the cases of out-and-out fraud, if you can't figure out who is REALLY sending the message, there's very little you can do.

How SPF Fights Back

Alden Hosting LLC has teamed with industry leaders like Microsoft and AOL to introduce SPF, a proposal to stop email forgery. To make spammers send mail from their real domains, instead of hijacking the accounts of innocent users.

SPF lets domains say what computers are allowed to send mail as that domain. If your domain uses SPF, and someone tries to send mail as you in Timbuktu (assuming, of course, your ISP is not in Timbuktu), your correspondent's ISP can reject the message, or just flag it for discarding.

The best part? You don't have to worry about it! Alden Hosting sets up the acceptable senders. Your correspondent's ISP does the checking. To users, SPF is a seamless process, protecting your email address without causing you headaches.