Unfortunately, Congress is trying to put a stop to that. Since the United States Postal Service will deliver tobacco products, HR 2813 was introduced in the House on June 8, 2005 "to make cigarettes and certain other tobacco products non-mailable".
For more information, go to thomas.loc.gov and do a search using the bill number.
The postal service said they cannot do this. They have to hire on more people to open every "suspected" package, etc, and they just won't do it.
The lawmakers have a fit over cigarettes passing through the mail, yet say nothing when it comes to child porno? Go figure.
When all ways to ship are taken off the table, there will always be "cigarette runners" willing to fill their cars and trucks with cigs and make deliveries.
Gov't agencies have forgotten about prohibition and how it was practically unenforcable.