The US Post Office was explicitly authorized by the United States Constitution, one of only a few such agencies. It has, since it's inception, been considered of paramount importance for a free people. In 1983 the Post Office was transformed into the Postal Service, a corporate style entity, with a board of governors acting as a corporate board. The Postmaster is no longer a cabinet position, but instead acts as the CEO of a corporation.
The USPS receives little taxpayer money, primarily for costs associated with overseas voters. Yet it provides reduced rates for library materials, books, and matter mailed by non-profit organizations, as directed by Congress.
It employs approximately 600,000 people and has nearly a quarter million vehicles. It costs the Postal Service about $8 million additional for each 1 cent rise in the cost of fuel. As you can imagine, their labor and fuel costs are off the charts.
The internet has radically reduced the volume of mail, but has not removed a single stop from any postal route. It takes the same amount of time and fuel to deliver one piece to every address as it does to deliver three. The reduced mail volume no longer covers the cost of 6-day delivery to every address in the country.
What sane businessman would want to buy it? Would you buy a USPS IPO?
I've heard many stories about lazy postal carriers, but with over a half million workers, there are sure to be a few undeserving of the public trust. How many large companies have as few complaints? Delivering over 660,000,000 pieces of mail to over 142,000,000 addresses daily is an incredible feat.
No, I don't think America should consider privatization. It really could not serve any useful purpose.