SPF - Sender Policy Framework |
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SPF is an open source standard that is emerging as a solution to prevent spammers from using fake email addresses. The following description was taken from the official SPF website at http://spf.pobox.com: Domains use public records (DNS) to direct requests for different services (web, email, etc.) to the machines that perform those services. All domains already publish email (MX) records to tell the world what machines receive mail for the domain. He connects from somewhere other than hotmail. When his message is sent, you see MAIL FROM: <forged_address@hotmail.com>, but you don't have to take his word for it. You can ask Hotmail if the IP address comes from their network. (In this example) Hotmail publishes an SPF record. That record tells you (your computer) how to find out if the sending machine is allowed to send mail from Hotmail. If Hotmail says they recognize the sending machine, it passes, and you can assume the sender is who they say they are. If the message fails SPF tests, it's a forgery. That's how you can tell it's probably a spammer. SpamFilter ISP looks up SPF DNS records for all incoming emails. If an SPF record exists, the query results can be any one of the following:
If the result is "Pass" the email will pass the SPF filter. Behavior for all the other failing results can be customized by the administrators in the SpamFilter GUI by adjusting the settings in the Settings - SPF Filter tab.
In SpamFilter Enterprise, each setting can be configured independently for each email domain.
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