all it takes is staged buyers. but fortunately for silk road's sake it's too small and amateur to interest anyone with an agenda.
I'm sure law enforcement & the DEA didn't think that idea up, at least after a few senators called for the site to be 'shut down'.
http://www.reuters.com/article/2011/06/08/us-financial-bitcoins-idUSTRE7573T320110608What good can undercover ops do when all drops are made via mail using prepaid 'postage paid' envelopes?
Simply put: It's impossible to trace them. The origin of those letters can't be determined in any possible way. They are vacuum packed as well so dogs wont know what's inside either.