Many options are normally enabled by default, this feature provides site owners with granular toggles regarding to whom site participants are able to send messages.
Site owners can set permissions on the basis of site role, such as Instructor, Teaching Assistant, and Student in many sites. As an example, participants with the Student role may send messages to all site participants when the associated Allow send to 'All Participants' option is activated by the site owner.
Go to Messages.
Select Messages from the Tool Menu in your site.
Select Permissions.
Select checkboxes associated with permissions.
To activate an additional permission, select the checkbox associated with the role and permission so that it becomes checked.
To deactivate a permission, select a checkbox that is already checked so that it becomes unchecked.
Note: activated sending options are visible to site participants when clicking the "To" text box while composing a message.
Select Save.
Select Save to apply changes.