NSA performed warrantless searches on Americans’ calls and emails – Clapper
– NSA used ‘back door’ to search Americans’ communications
– Director of national intelligence confirms use of new legal rule
– Data collected under ‘Prism’ and ‘Upstream’ programs
stoporgangstalking 
The NSA is not the only organisation to tap people’s emails and phone calls.
I think they know, but at least this is a start.