I need to set uddeim with the following scenario:

user group 1: to be able to receive messages, but cannot reply or start new
user group 2: to be able to receive messages, can send only to ug1 and ug3
user group 3: to be able to receive messages and to send just to ug3
user group 4: to be able to receive messages and to send to everyone (ug1, ug2 and ug3)

i'm using CB 2.0.6 on joomla 3.3.6, i have developer subscription here so have all the additional plugins which might help me.

Any idea how can i achieve what i want?

I am sorry but I do not think that this is possible without any code changes.

Hello,

A simplier way :

Is it possible to allow creating new message only for superusers ?

Thanks !

Yes, block all users except user admins in uddeIM backend and make the menu link available for admins only.