John,?
Since you haven't given us much info it's difficult to give you a solution.
Is your group restricted?
If not, why not make it restricted?? Then you could control new member entry and the process they must go through prior to actually being able to post of view or send & receive email messages.
This also is an advantage since you can impose moderation on the new member in addition till you're satisfied they are legit and not out to hack you.
My view is that unrestricted groups quickly gather unwanted members.
--
Bob Bellizzi
The Corneal Dystrophy Foundation
