You can segregate conversations between your internal team and external clients/stakeholders by using the grey Private Comment or Note (formerly called Dev Note) comment types. These types are only viewable to you and collaborators (users with an InVision account that you added via the + button on your prototype). If you send a share link to an external reviewer, they won’t be able to see Private Comments or Dev Notes. Users with the Reviewer role in Enterprise will not be able to view these comment types unless this setting is switched on from the member permissions page by an Enterprise account Admin.
To converse with your external users, select the pink Comment comment type from the drop down menu after you type your comment, then click Send. Choosing this comment type makes the comment viewable both within the app and via URL shares.