Some customers would like to disable the possibility of selecting certain Databases for an Email/SMS/Push send. This is because they work with Queries and Contact Lists, and would like to avoid the risk of contacting their entire Databases with a single communication.

To achieve this, I believe a checkbox to set a Database as "not visible for selection when sending" would be ideal. This could be within the Database Settings area, maybe under Security Settings where the other checkboxes for permissions are, and managed by Org Admins.