The Sender Policy Framework is an open standard specifying a technical method to prevent sender address forgery.
http://www.open-spf.org/
Email Hosting Providers
Get access to data on 166,481,613 websites SPF Customers. We know of 127,044,438 live websites using SPF and an additional 39,437,175 sites that used SPF historically and 9,102,547 websites in the United States.
Get a list of 166,481,613 websites using SPF which includes location information, hosting data, contact details, 127,044,438 currently live websites and an additional 5,343,867 domains that redirect to sites in this list. 39,437,175 sites that used this technology previouslyand 9,102,547 websites in the United States currently using SPF.
Countries
Financial
Group
Region