It is definately possible. This would require adding a new field in the phpBB_users database table that increments by one each time that user submits a PM. A new field would then be added to the profile_view_body.tpl to show this value .. optionally limited to Admins and/or moderators only. Let me know if you want to persue this MOD.
ErDrRon (Yes, I really am an ER Doc)
Author of the Admin Voting, Retroactive Signature and Edit Post Date MODs. [Unofficial MODs, of course]
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