Contacts Do Not Receive Notifications of Task Updates

• The task is marked as not visible to client – http://prntscr.com/hxjs26 keep in mind that this checkbox may not be shown if project option Allow customer to view tasks is unchecked (see #2)
• The project option for customer to see tasks is unchecked – http://prntscr.com/hxjrw4
• The email templates in Setup->Email Templates for task updates is disabled.
• Navigate to the customer profile in admin area click on the Contacts tab and open the contact(s), make sure that this contact has Tasks email notifications enabled, project notifications are different from tasks.