Snip... Two, recent laws passed prohibit the mailing of tobacco products. There's a few others...
USPS News Release: New Mailing Rules for Tobacco Products Set for Summer
USPS still allows shipping of tobacco products, even under the Prevent All Cigarette Trafficking Act. FedEx & UPS picks up any shipments banned by USPS. ;-) Example: Quantities larger than what would fit an Express Mail envelope/box.
The evil Harper in me keeps wondering how much the Chinese Govt has been quietly "lobbying" the US Govt. on the little issue of Chinese produced goods shipments being seized in customs. Sigh, I've lived in DC too many years!