We have used this a few times – and it has tracking. Moves pretty fast – about 5 days.
If you need to track International Mail through the US post office consider using Global Express Guaranteed or Express Mail International services. Delivery information is available to most countries for C-series customs label numbers that come with Regular Priority Mail International, or the Medium and Large Flat Rate boxes. You can also receive confirmation of delivery when using their Registered Mail service in conjunction with the specific class of mail you use.
We (Dave & I) personally have used FedEx, DHL and Global Express. Global Express was actually quicker took 5 days to come from Seattle to Cotacachi. DHL & FedEX both costing considerably more took over a week. All three options offer online tracking so you can see where your envelope is. For our dollars – Global Express is the winner.