I have a Google Group that i need to add an email address to. It's an invite-only group but when i try to add the address (which is hosted by google apps) it says "Google Groups will not invite 1 user with a restricted address"

What does that mean?

"It isn't possible to add certain types of email addresses to Google
Groups (notably, addresses that start with webmaster, postmaster or
info). Because these restrictions are in place to prevent abuse,
there
is no way to bypass them. If you try to add one of these addresses to
a
group, you'll see the message "Google will not add 1 user with a
restricted address."
"
See
http://groups.google.com/group/Managing-Your-Group/browse_thread/thread/d892e372c1e62a2b/06a3d2c93936b6bc