If you are in the Users Manager role you can decide if a notification is sent to the author of a comment when its state is changing. First, open the Engage Process Admin Center tool by pressing the application launcher button 
on the top-right of the window and then select Admin Center (you can login directly to it using the link https://admincenter.engageprocess.com).. Select the Notifications tab there.
Currently, a notification is sent automatically to the author when:
- Someone reacts to the comment
- A modeler accepts the comment
- A modeler rejects the comment
Uncheck the corresponding box if you want to block this type of notifications for all users in your organization.
A notification about a new comment is only sent to the members of the comments notification list defined by a modeler (for shared processes) or by a publisher (for published processes). If this list is empty or all users in it are not members of the organization anymore then nobody will receive a notification. To avoid such a situation a user manager can specify default comments notification e-mail address.
This is also a place where you can disable emails sent automatically to all users authorized to view the shared version of the diagram. Just uncheck the a new diagram was shared box.