How Much SPF Protection Do You Have?
Jul 14, 2009, 17:31 (1 Talkback[s])
(Other stories by Sonny Discini)
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"SPF is an open standard specifying a technical method to
prevent sender address forgery.
"SPF is the protocol-level identification of the delivering mail
server, and it is usually invisible to recipients. It is mirrored
in the Return-Path header, the address to which mail delivery
errors (or bounces) are sent. For individual e-mail addresses or
small domains, it may sometimes be set to the user's e-mail
address. But for larger and more professionally managed domains, it
is usually a domain related to the mail server that sent the
"SPF protects the envelope sender address, which is used for the
delivery of messages. This allows the owner of a domain to specify
its mail-sending policy by specifying which mail servers are used
to send mail from the domain. The technology requires two sides to
participate: The domain owner publishes this information in an SPF
record in the domain's DNS zone, and when someone else's mail
server receives a message claiming to come from that domain, the
receiving server can check whether the message complies with the
domain's stated policy. If the message comes from an unknown
server, it can be considered a fake."