
Particularly with the rise of challenge/response as a spam filtering technology, more is being made of the intellectual property of spam filtering technologies.
Intellectual Property Rights (IPR) in Anti-Spam Technology - www.shaftek.org/publications/asrg-ipr.html
Spam Blocking Patents - rentzsch.com/notes/spamBlockingPatents
Filter-in method for reducing junk e-mail (6,112,227)
Method and system for filtering electronic messages (6,199,102)
Method for restricting delivery of unsolicited E-mail (6,691,156)
System for eliminating unauthorized electronic mail (6,868,498)
rPost patents - www.rpost.com/company/intellectual-property/patents
Yahoo! Inc.'s statement about IPR claimed in DKIM documents - https://datatracker.ietf.org/ipr/716/
Electronic mail filtering by electronic stamp (5,999,967)
Method and apparatus for enabling a fee to be charged to a party initiating an electronic mail communication when the party is not on an authorization list associated with the party to whom the communication is directed (6,587,550)
Third-party e-mail authentication service provider using checksum and unknown pad characters with removal of quotation indents (6,640,301)
Message filtering techniques (5,619,648)
Automated collaborative filtering system (5,884,282)
System and method for filtering unsolicited electronic mail messages using data matching and heuristic processing (5,999,932)
Method and system for filtering unwanted junk e-mail utilizing a plurality of filtering mechanisms (6,023,723)
Apparatus and method for controlling delivery of unsolicited electronic mail (6,052,709)
Method and apparatus for filtering junk email (6,321,267)
Value-added electronic messaging services (6,650,890)
Method and apparatus for filtering e-mail (6,654,787)
System, method and article of manufacture for preventing the proliferation of unwanted electronic messages (6,687,740)
Comprehensive anti-spam system, method, and computer program product for filtering unwanted e-mail messages (6,732,157)
System and method for defining, refining, and personalizing communications policies in a notification platform (6,745,193)
Electronic mail filtering system and methods (6,772,196)
Processing of textual electronic communication distributed in bulk (6,842,773)
System and method for constructing and personalizing a universal information classifier (6,901,398)
Candidate Chaser (6,381,592)
A method for managing bulk e-mail distribution (6,631,400)
System and method for counteracting message filtering (6,643,686)
System and method for counteracting message filtering (6,915,334)
Hormel loses bid for spam trademark (EU) - www.theregister.co.uk/2006/10/04/hormel_loses_spam_trademark_appeal/
Spam Arrest LLC Puts Final Can on Hormel's Spam Trademark Action - www.spamarrest.com/pr/releases/20040528.jsp
Hormel Spam trademark case canned (Spambuster) - www.theregister.co.uk/2005/01/31/spam_ruling/