Thanks for the voice of reason, retired. Always appreciate having the tug of war diffused, it keeps us off topic, fight them not ourselves after all.
The method of enforcing this is pretty easy, actually. If you can't legally mail an ecig to a state, and your business continues to do so, the records will eventually be looked at, and you will be fined pretty heavily. This already happens with other items. You may get away with 100's of shipments, but when you finally do get pinched, they will look over your shipping records and determine how many offenses you have committed, now that they have probable cause to investigate your business practices.
The saving grace of this may be that the law has no hard definition of what an ecig is. Mailing a mod may not be covered by this law, as it is not capable of vaporizing anything. Mailing an atty may not be covered because it also is not capable of vaporizing anything without a battery. E-liquids are questionable, since arguably they are the 'tobacco' product (i.e., they contain nicotine, and we need a label for it to control it), but technically, there is no law against mailing nicotine, just smokables and ecigs. I think that mailing cigalikes would be doomed under that law, but everything else is questionable. The question remains if any suppliers would be willing to risk getting heavily fined or shutdown if the law was interperated against their position, rather than for, which would make it just as damaging as if it was all-inclusive.
This is a big deal, and need a ton of support to get it shut down, if possible. Being as there is already a dollar sign attached to the bill, I think the battle is determinedly uphill, but that doesn't mean that it cannot be one. Time to get out of the armchairs and be activists. If you ignore this, all you are doing is helping set a legal precedent that will devour the vaping nation one state at a time.