I recently received a package of about 70 full matchbook covers while in Miami. There doesn't seem to be a problem mailing within the US. However, I had to return to Mexico (aha! says the reader). Fortunately we are pretty paranoid so we got to the airport about 3 1/2 hours early and my carry on bag was searched and the matchbooks withdrawn. Two options: accept confiscation and I got a real bollicking, or, and security was pretty nice about it, I could take the matches out and keep the covers. The guards were serious but couldn't believe someone actually collected such stuff.
I was also informed that under the present circumstances I was lucky not be taken for interrogation and possibly prosecution. I was also told that the package would have been discovered in my checked luggage and there the problem gets worse as I would have been pulled from the flight and the flight would have been delayed, causing major security problems and most likely prosecution. You only need to be told once. Needless to say I am now a collector of matchbook covers.
Regards
chris bolton