Are newsgroup names CaseSentitive?

[barney]

I'm having a little issue with my ISP's news server. A group name that
downloaded from their server has some capitalization in it.  Google
groups shows just lowercase letters in that ng name, which is what I
expected it to be.  I was able to subscribe and read messages OK on the
NTTP server, but replying to any post fails unless I manually change the
To: address to match the capitalization on the server.

Is this a problem with mozilla, or with my ISP?

thanks