According to USPS Publication 227:

It is illegal to mail all snakes, spiders, poisonous insects, poisonous reptiles, and poisonous animals [b]except scorpions[/b].

Huh?  I didn't realize that the National Associaton for the Advancement of Scorpions had so much influence.  [:\]

By the way, it's also illegal to mail any "flammable material".  Am I the only one who's noticed that paper is flammable? [>:/]

Huh.  That explains why none of my snakes have been getting through.  I'll start UPS-ing 'em.
No poisonous reptiles either?  Guess Rosie O'Donnell will have to go by commercial truck.  Oh, yeah... she probably has to anyway.

Sorry, but paper is not flammable.
For a product to be flammable , it has to have a flash point of less than 100 degrees F .

Paper has to be heated to a temperature of more than 100 degrees before it wil ignite.

Yeah, but what if I doused my scorpions in gasoline?  Could I then mail my flammable scorpions?

Hmmm...  But we see wire cages of bees all the time at the MPO/Sectional Center(Atlanta).  Cages with full grown chickens and ducks.  Boxes with  baby ducks and chicks.

The Center For Disease Control gets boxes with biohazard tages in DayGlo all over them daily.  Those get Tender Loving Care...

Plenty of the HazMat in the Post Office.

556mm, where did you get that definition of "flammable"?

Using the 100 degree F standard, black powder isn't "flammable" either.  I don't know if even gasoline would spontaneously burst into flames at a hundred degrees -- it seems as though there should be thousands of flaming lawn mowers every summer if it does.  

The 100 degree F standard only applies to liquids.  There are other standards for solids.  Also, the Dept of Transportation considers any liquid with a flash point of 141 degree F or less to be a flammable liquid and to be regulated as a hazardous material.
Also, Matt VDW, the flash point is the temperature at which a liquid will ignite in the presence of an ignition source.  You were thinking of the ignition temperature, which is much higher.

OK, I found a definition from the US Department of Transportation:

Flammable Solid - Any solid material (other than an explosive) which under normal transportation conditions is liable to cause fires through friction or retained heat from manufacturing or processing.

So according to DOT, paper is combustible but not flammable.  It seems that letter senders are off the hook.  [;)]

By the way, even though live scorpions can be legally mailed, they are subject to "legal restrictions on who may mail these items and how they must be packaged".  Don't just slap a stamp and an address label on your scorpion and drop him in a mailbox.

451 degrees F.

contras21... sounds like a book "Fahrenheit 451" I can just see it now.  [:)]
Nuckles.