Hi there,
I suspect that this happens because you have enable "Notify moderators on new posts" and "Notify moderators on new replies" at
Backend>Components>EasyDiscuss>Notifications>Emails as shown
http://prntscr.com/c96u6v under permission and as i further check, under "Building Projection" category at
Backend>Components>EasyDiscuss>Category>"Building Projection">moderators almost all "group user" were tick as shown
http://prntscr.com/c96u9f under moderators. That why almost all of user get the email notifications. Can you try to disable "Notify moderators on new posts" and "Notify moderators on new replies" or set minimum user for moderators? Please give it a try and see how it goes
.