Premium 360 subscribers have the ability to message all users in a given list in Edelweiss360.
From messaging everyone who reviewed a specific title…:
…To sending a message to your Contact list:
If you want to send a message to a select number of users from a certain list, click the number in the blue bubble and check off the users you’d like to message, and uncheck the users you don’t:
Users you message through 360 will receive it in their notifications center in their Edelweiss account: