It doesn't take much imagination that these days each such address is kept, and that the three-letter agencies have a sample of everyone's handwriting, in case it is needed.
http://www.nytimes.com/2013/05/04/us/where-mail-with-illegib...
I guess it makes sense that every piece of mail is "photographed" at some point...in the sense that a scan is a photograph. So the act of photographing each mail isn't a surprise.
But, as opposed to the Verizon and PRISM cases, when you send a piece of snail-mail, you are literally sending it to the government to be handled, have its "metadata" read and recorded as necessary as a means for it to be sent to its destination.
On the other hand, the aggregation of data and retention of such may not be something we're all happy with, so what's the policy on that?
But I don't expect the metadata to be retained indefinitely (except if I requested special services such as tracking or proof of delivery). That has nothing to do with delivering my mail to its destination, just like the phone company retaining my personally identifiable GPS data indefinitely has nothing to do with providing phone service.
