The government's insatiable need to know everything about your communications with everyone else doesn't stop with email. Good old-fashioned snail mail is also under universal scrutiny.
"As nightfall does not come all at one, neither does
oppression." -- William O. Douglas
The government has long had the authority to record the information on the outside of mail covers, but this required as a practical matter individualized suspicion and monitoring.
Now technology has allowed much much more than this. From the NYT (7/03/13) it appears that old fashioned mail-cover monitoring is:
... a forerunner of a vastly more expansive effort, the Mail Isolation Control and Tracking program, in which Postal Service computers photograph the exterior of every piece of paper mail that is processed in the United States — about 160 billion pieces last year. It is not known how long the government saves the images.
I'll tell you how long the government saves the images -- as long as they damn well please.
I'd reckon that there isn't any instance of communication in this country, other than face to face, that is not known to the government. Of course in the cases of emails and telephone calls, not only the fact of the communication but also the contents of those communications are also known.
Bit by bit, we've built the mechanisms of a dictatorship. Not that we have one now, but should one come along, we will be defenseless before it. The real danger is that we won't necessarily see it coming. Nightfall does not come all at once.