I like to check on the postal system by sending or receiving packages. Please shout out normal company that send USPS.
Everthing I order through large commercial retailers ship UPS. USPS is actually dead last when it comes to shipping commercial packages...
Amazon: UPS REI: usps, ups, fedex Chegg: UPS Bestbuy: UPS--i think
Most, if not all, e-cig eliquid business use USPS to ship their goods. Priority flat rate or padded envelope. Hint to vendors -- eliquid is a great cover, especially if you are shipping liquid Alp, LSD, etc., just pick a generic name "Hangman's Noose Nic Juice, Inc." . . .