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
DNS-based block list information/database. Resource to find out information on DNS block lists and check IPs to see if the are block listed in over 100 blacklist in just seconds.
"...allows you to have private conversations over instant messaging by providing: Encryption [...] Authentication [...] Deniability [...] Perfect forward secrecy ..."