SPF and DMARC Information and Tools

DMARC and the Continuing Fight Against Spam:
http://thoughtsofanidlemind.wordpress.com/2012/03/28/dmarc-spf/

Domain-based Message Authentication, Reporting & Conformance:

http://dmarc.org/

Sender Policy Framework:

http://www.openspf.org/

Email Resource and Delivery Tools Site:

http://www.unlocktheinbox.com/
DMARC Wizard:
http://unlocktheinbox.com/dmarcwizard.aspx

DNS Lookup Tool, Reverse DNS Lookup Tool:

http://www.dnswatch.info/

Whitelist Provider for Email Filtering:

http://www.dnswl.org/

Beveridge Tools:

http://tools.bevhost.com/