First of all this is a great component! Second: since 1.6 it is not possible for me to check the box: unregistered visitors may send a message. Where can i put this on? This whole component is kinda useless if only registered users may send a message:P
A PMS usually allows to send internal messages only.
In uddeIM 1.5 there was a pre-release of a "Public Frontend" for testing purpose implemented. From uddeIM 1.6 on this has become a "Premium Plugin" since this is not a basic functionality of an PMS.
You find more infos about the Premium Plugins on my dev site.
uddeIM & uddePF Development
CB Language Workgroup
CB 3rd Party Developer