Who says you aren't buying stuff on ebay? Who says you actually have pills in the envelopes? I would start mentioning to the delivery guy...."I must stop buying these hats pins (or marbles) on ebay for my collection" or something stupid like that!
I really don't think a delivery person would ever "turn" you in. Isn't it against the law for the actual delivery person to open/peak/look what is in your package??????