Hi,
I just released user-inbox 0.8.0. It is ready for CUBA Platform version 7.2 and furthermore allows sending messages to multiple receivers. Check it out at GitHub - mariodavid/cuba-component-user-inbox: CUBA component that gives users a mailbox for user-to-user and system-to-user messages.
Also, there is a new example, based on CUBA petclinic that uses the user-inbox addon: GitHub - mariodavid/cuba-example-using-user-inbox: CUBA example using user-inbox addon
Here are some demo usages from the example:
Manually Sending to multiple receivers
Using Sharing feature
Programmatic Creation of Messages
Cheers
Mario