I've posted a new build for Private Messages in the downloads section (members only).

New Functionality Includes:-

• Private Messages now supports a minimum of 4.5.5+
• You can now restrict who can send messages by role. In view options, you can select "restrict view permissions" and pick the roles allowed to send messages. Roles that aren't allowed to send messages will still be able to accept messages.
• You can now pick display name as an option for showing user labels. Display name will now be the default option.

Fixed Bugs Include:-

• Fixed an issue with quoting messages.

Thanks again for your assistance.