properties of your newsgroup account where you set up the e-mail address and reply-to address. Add some extra characters to these e-mail addy's to ensure that a harvester that collects will be scooping up an invalid e-mail address...example: someone@NO
SPAMsomewhere.HEREcom.

This *may* not be possible, it depends on the ISP, not the browser.

Some notes: Important to mung the address to the right of the at sign,
since any spam finds no such server. Next, some / most spamware can
search for and remove "spam" or other common words from a link.

What I had to do after being autospammed - set up two new addresses.
My ISP only allows people with valid accounts to send or recieve
messages. I use one as a throwaway. Hate to do it, because the spammers
will eventually harvest it and the server will have to turn the messages
away. But I tried....
My second address, in my sig, is spelled out. It is a valid address,
it works, but it is NEVER put on the web in it's full form.
Unfortunately, it's just a matter of time till somebody's infected
computer will start to spam me. Just like atomic decay.

I would NOT use a reply-to address in my messages, unless you want
that address being spammed as well.