How can Private Message sending be disabled for members not yet activated?

[edgeless]

Situation: Verify Email address in Registration is enabled. Moderate New Members is enabled. The Registered Users usergroup has PMs disabled (i.e., Private Message Permissions > Maximum Stored Messages is set to 0).

EDIT:
I stated this wrong in my initial description, and I apologize. Incorrectly stated on my part was the point at which new users are able to send Private Messages. I said that it was after clicking on the activation link in the registration email. That is wrong! Instead, they are able to send PMs before clicking on the activation link in the registration email. Once they click on that link and become activated and placed in the User Moderation queue, they are unable to send PMs anymore. And they cannot send PMs again until they are passed via post count promotion to the full privilege usergroup. So that's the problem. All a user has to do is fill in the registration form and submit it in order to start sending PMs. There has to be a way to fix that?

I don't want unactivated users to be able to send Private Messages to other members. They should not be able to send PMs at any point before they are automatically promoted by their post count.

So is there an easy fix for this problem? Again, I'm sorry for incorrectly describing it the first time.

Thank you