The Sender Policy Framework is an open standard specifying a technical method to prevent sender address forgery.
http://www.open-spf.org/
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Get access to data on 164,753,872 websites that are SPF Customers. We know of 124,023,096 live websites using SPF and an additional 40,730,776 sites that used SPF historically and 8,784,880 websites in the United States.
Get a list of 164,753,872 websites using SPF which includes location information, hosting data, contact details, 124,023,096 currently live websites and an additional 5,462,051 domains that redirect to sites in this list. 40,730,776 sites that used this technology previously and 8,784,880 websites in the United States currently using SPF.
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