I'm sorry, but I just don't understand the logic. When active
participants send e-mail to your list, you want it checked against a
subscriber list and forwarded to you for verification if it doesn't
match. On the other hand, you want to accept any and all messages coming
from usenet without verification. This is like installing an alarm system
on your back door while leaving the front door open. The simplest
solution is to leave the back door open as well.
Eric