The United States Postal Service offers package tracking and receipt confirmation as do United Parcel Service (UPS) and Federal Express (FedX). Here is the difference between the services; with either the UPS or FedX service you can follow an items journey from start to finish with intermediate stops identified and times in and out noted to the minute. With the US Post Office system I have never seen an item so much as entered into the system until long after the item was actually received. It is the worst tracking system I have ever seen but unlike its commercial counterparts, which are a free service, you have to pay extra for it from the Post Office.
Oh, and those green "Return Receipt" slips that are supposed to find their way back to the sender after successful delivery of a package or letter and signature by the recipient - you'll see 1 out of 10 of those find its way back to you if you're lucky. Once again, an extra cost service that is horribly broken.
I give you this quote from a web site* I ran across when I got curious about postal rates:
"The Postal Service has little oversight, and virtually no accountability. It is an independent federal agency with commercial responsibilities. It has an annual budget of over $68 billion handling over 200 billion pieces of mail, yet it does not have to report to the Securities and Exchange Commission, comply with the Federal Trade Commission's truth-in-advertising rules, nor adhere to local government zoning and traffic regulations. It defines the scope of its own monopoly and, in some respects, regulates its competitors (such as mail receiving agencies).
Under current law we cannot effectively motivate the Postal Service to improve when service deteriorates for a particular mail class. The best we can do is to issue an advisory opinion which the Postal Service is free to ignore and generally does."
*
http://www.cagw.org/site/News2?page=NewsArticle&id=7773&security=1242&news_iv_ctrl=-1