Quote Originally Posted by mtjade2007 View Post
I don't know how it is determined that it is illegal. I searched USPS web site and could not find clearly spelled out words that say it is illegal to ship any particular photographic chemical. ....
Not that I disagree but I believe it is UPS not USPS that was specifically mentioned. Although it gets complicated now that USPS handles the final delivery for some packages from other shippers (UPS may be among them, not sure).

The UPS hazardous material details are here: