Most people usually don't use their real email.  They create a fake
email which is their reply to email, one that is easily picked apart by
people to determine their email address, but one that an automated process
(like a spam bot culling newsgroups for email addresses) can't easily pick
apart.

   See my signature, or others in this group, for some examples.

With google groups, you're in a catch22 because you probably can't create a
google/account with a fake email.

At home, I use outlook express as a news group reader.  In outlook express
you can put in whatever made up email you'd like.

..

I'd create an email thru yahoo or gmail or something, and use that as my
"public email" that is spammable.

I don't use Google Groups for posting, but I suspect that if Google
Groups itself shows your email to you but not other people's email, then
your email is only being shown to you because it's you looking at it.
That is, I think it's likely that Google Groups is applying the same
address obfuscation tactic to your address as it applies to every other
address.

Try viewing your post on Google Groups without being logged in.

But do note that that only relates to how Google Groups _displays_ the
posts.  It does truncate email addresses when displaying posts, but it
doesn't (and can't) actually do this in the post itself.  It's just the
newsreader side of things.  This means that your email address is still
visible to anyone else using other newsreaders.

This is where the suggestions from Nicholas and Sloan come in.  The only
way to prevent your real email from being visible to spammers is to not
post your real email.  Traditionally, you'd post something that can be
readily converted by a human to a real email address, but which would be
difficult or impossible for an automated system to extract.

Pete