Usually we use the U.S. Post Office - or - The USPS Pirate Mail*
If you're not familiar with Pirate Mail - It's all legal and fair; IMO, it's just that the USPS knows that their prices are high and are hurting American Businesses who can have the Chinese to compete using their Government subsidized Postal Services. Plus, when I was a little kid,
1st Class Postage was just 2¢, and now it's 58¢+ just to send a letter to three houses down the street!
However, we do seek the least expensive way to send to you. Sincerely, Bob