New User Sandbox

Rather than the usual sandbox plugin which requires the admin approval first, how about sand boxing all new users until the user verifies their e-mail address.
I know allot of spam bot post dents as soon as they have registered and think this will help to keep the public activity scream clear.
do spam bots tend to eventually verify their e-mail address?

Using sandboxing, akismet/typepad anti spam should help keep a handle on spam.
any dents/user bio's that the system thinks is spam should be put in a spam que for admin approval. if its not spam the admin marks it so and the system learns.
If its spam the admin can delete it from the system.
If the user posts a dent that is deemed as spam, then continues to post more dents which are deemed spam, the user should then be sandboxed and put into a que for admin approval.
Should the admin deem the user to be a spammer, the admin can delete the user which should in turn delete all dents/posts.
Having links checked against phishtank and surb.org or other spam database can help categories spam where the spammer posts a single link to multiple groups.

I may be wrong on this idea and know that you carnt stop spam completely from happening but keeping spam posts out of the public and group streams should help allot for the user experience.