A big update to Organizations this week. If you allow your Organization shared access to tickets (find out more) then those end-users part of that Organization now have the ability to "Subscribe" to the Organization, which means they'll get an email sent to them whenever a ticket is created or updated under that Organization.
You don't need to turn anything on for this ability. If the organization is "Shared" then end-users simply need to navigate to the Customer Portal, click on their Organization tab and click "Subscribe".
Fixed an issue with default groups where, if the assignee was now deleted, Zendesk would throw an exception.