Here's an issue we're running into. People will often make a lot of sequential changes to a bug, and depending on whether or not the workflow screens directly support doing all those changes at once, subscribers to change notifications may get blasted with emails that are all related to the same bug.
Example: someone writes up a bug, goes back and edits a custom field that wasn't on the bug creation screen, attaches a screen shot, then assigns it to someone. Anyone subscribed will get four emails for one bug being created.
Suggestion: have Jira wait x minutes on the most recent change to an issue to let it "settle" before sending out a notification email, and have that email contain all the changes at once.