check a domain's SPF (Sender Policy Framework) record, löst includes gleich mit auf | include:_spf.example.com = TXT-DNS-record von _spf-subdomain (dig ... txt) | SPF-Test mit gutem Log (redirect...) http://vamsoft.com/support/tools/spf-policy-tester
P. Bobade, S. Wadekar, N. Pagare, and K.S.Warke. International Journal of Innovative Science and Modern Engineering (IJISME), 2 (2):
14-15(January 2014)