Abstract: «Email address forgery is a problem on the Internet today. Domain owners want to control the use of their names in email, but are helpless because they lack the means. This document introduces a language for domains to make email-related declarations in DNS. It defines in detail one possible sender authentication scheme for domains to describe the hosts from which they send mail. SMTP receivers can use this scheme to detect sender forgery.»
http://www.ietf.org/internet-drafts/draft-mengwong-spf-00.txt
See also: AOL publishes SPF record, Slashdot: SPF Design Frozen and Status Report on the SPF draft