Corporate firewall blocking based upon site urls

I am a bit puzzled by this. seems that a fair portion of a website i code for and support’s customers are unable to access it at work, with messages similar to this one:

[Based on your corporate access policies, access to this web site ( ) has been blocked because the web category “Weapons” is not allowed.

If you have questions, please contact your corporate network administrator and provide the codes shown below.
Notification codes: (1, WEBCAT, BLOCK-WEBCAT, 0x003a3872, 1243526187.903, AAAAXgAAAAAAAAAAyf8AEP8AAAA=,

the site sells outdoors gear - and amongst other thing, swiss army knives. that’s hardly what i’d call weapon.

anyway - what software do you know that does this kind of block on a proxy/firewall level, does it rely on any online directories or does it analyse content as it comes in, is there a way to appeal against classification…

as a whole, open to ideas how i can figure this out and rectify it - reports thus far have been from women and not very forthcoming…