I just saw http://www.wpxi.com/news/news/local/pittsburgh-postmaster-accused-opening-packages-con/nnfsw/ And it reminded me how a Vendor and Client should use legit addresses. If a malicious postal agent is trying to score DNM packs thay can pick them out and use a search engine web site that offers reverse address look ups (free and readily availible) they can see if a return or destination contains fake elements. Vendors can use them to see if a client is giving out a name that matches with the records. They don't work 100% of the time, but there are like 5 or more of them so you can tell if the name address/pair is legit or not. Also these things will correct buyers mistakes that often lead to "undeliverable as addressed"
Also when making a PGP, make sure your username or email name (when direct dealing) matches your usernme. Vendors can't know that "therealdabtard" goes with the key "boofyournewrc@sigaint.org"
Your ideas are intriguing to me and I wish to subscribe to your newsletter.