Your reader program can only filter on email domains and not newsgroup domains? That's strange, I haven't heard of any program that does this, or anyone filtering by email domain alone. Most people just filter out the google usenet domain if anything, in which case I won't get filtered out.
The huge advantage of using gmail for my newgroup (and other) email is that I get zero email spam. I used to use my old ISP email address on the newsgroups, but I got continually spammed. Gmail seems to know how to deal with it all. So no need for me to obfuscate my email address like many do on here.
Dave.