Restrict Private Message sending (as opposed to restricting Private Msgs altogether)

[TJFweb]

Hi,

A lot of plugins / extensions use Private Messages as a way of communicating information to users (i.e. Warning alerts, Arcade challenges, RPG information). However, if a usergroup does not have permission to use private messages, then they won't be able to receive any of these alerts.

A hack which restricts a usergroup's ability to send private messages while still allowing them to receive them would be very useful in my opinion.

Thanks!