http://dmoz.org/Computers/Internet/Abuse/Spam/Filtering/
AppRiver
http://www.appriver.com/arm/novell_exchange.htm
Apparently (according to Firefox) broken redirect
Bright Mail
http://www.brightmail.com/
Redirect
Despammed
http://www.despammed.com/
Dead
Dynacomm
http://www.dciseries.com/products/ifilter/
Redirect
Email Filtering
http://www.emailfiltering.co.uk/
Redirect
Email Sifter
http://www.emailsifter.com/
Redirect
EMF Systems
http://www.emf-systems.com/
Redirect (same as Email Filtering)
Filter Spam
http://www.filterspam.co.uk/index.html
SCAM
Mail Zapper
http://www.mailzapper.com/
Redirect
Pyzor
http://pyzor.sourceforge.net/
Open Source Project that has not been updated in four years.
Sender Policy Framework
http://spf.pobox.com/
Redirect
Spam Resistor
http://www.spamresistor.com/
Redirect
AppRiver
http://www.appriver.com/arm/novell_exchange.htm
Apparently (according to Firefox) broken redirect
Bright Mail
http://www.brightmail.com/
Redirect
Despammed
http://www.despammed.com/
Dead
Dynacomm
http://www.dciseries.com/products/ifilter/
Redirect
Email Filtering
http://www.emailfiltering.co.uk/
Redirect
Email Sifter
http://www.emailsifter.com/
Redirect
EMF Systems
http://www.emf-systems.com/
Redirect (same as Email Filtering)
Filter Spam
http://www.filterspam.co.uk/index.html
SCAM
Mail Zapper
http://www.mailzapper.com/
Redirect
Pyzor
http://pyzor.sourceforge.net/
Open Source Project that has not been updated in four years.
Sender Policy Framework
http://spf.pobox.com/
Redirect
Spam Resistor
http://www.spamresistor.com/
Redirect