Sorry if this has been mentioned already.
There is a NATGEO show called "To Catch a Smuggler." Watch the episode called "Hidden Heroin" for an inside look at how a USPS bust goes down.
I need to re-watch, but I think they left out the information on WHY they profiled the packaged, but you get to see what happens after they suspect drugs are in a package, and all the processes that lead up to a CD.
They start the CD process towards the end of the episode but unfortunately it ends without actually witnessing the CD.
Something I noticed is that the investigators were SHOCKED that the person used his real name for the delivery. Apparently the person had an arrest record for heroin already, so it made it easier for LE to tie the package to him. Maybe you shouldn't ALWAYS use a real name, especially if you have any kind of drug history on your record...
There are probably more USPS busts to be seen in other episodes, but I have only seen the first two episodes. It's on Netflix BTW.
EDIT: Confirmed, episode 3 has more USPS busts. They show agents using XRAY machines to find concealed drugs.
Thanks for the info! I didn't know about this one. Good point about the prior record being a factor when it comes to linking packages to addressees. Further reason NOT to drink and drive or use and drive. Keep those records pristine if you can.