[jefferyepayne]

I got this off the USPS web site:

Shipping Instructions for Matches

Safety Matches

Safety matches have treated match heads that will only ignite when struck against a specially prepared surface like a match book, card, or box. Safety matches may be shipped domestically using ground transportation. Safety matches may not be sent by air or mailed internationally.

Strike-Anywhere Matches

Strike–anywhere matches will light from friction against any surface. Strike-anywhere matches may not be mailed domestically or internationally.

So you can send 'safety' matches through the mail domestically by ground. I don't know whether Diamond Matchbooks include safety matches or not.

jeff