In order to ensure that all who need get notifications about changes to an issue we introduced the possibility to subscribe to issues. You can add yourself or another user as subscriber to an issue. As of the September release we automatically add assignees and reporters of an issue to the subscriber list. This means you will get a complete picture of who gets notified about changes to the issue when you click on the “subscribers” link on an issue detail.
Also included in this release is the possibility to unsubscribe from the issue notifications by clicking on the link “I want to stop receiving emails about updates to this issue” in the email notification. You will then no longer get notification emails.