Notification emails should contain headers indicating the notification details to support automated filtering

Copied from a request made for JIRA Studio:

It would be beneficial so we can manage the volume of emails from JIRA if there were email headers set which indicates what properties in the issue have changed. Sometimes other parts of the issue like the Description, etc. are included even when they haven't changed.

Ideally it would be helpful to be able to filter when the change notification is because either a comment, the description or the assignee has changed.

Also, it would be helpful to detect whether the version that an issue has been moved to matches a particular condition (i.e. an issue has been moved into an iteration).

This probably isn't a Studio enhancement (or maybe it is), but may actually be a JIRA enhancement. But it would really help us better manage the email volume.