Redmine

This is not to be confused with another useful proposed feature that would do digest emails for notifications.

This would aggregate a group of changes to the same issue over a specified period of time (say 5,10,20, minutes) into one email notification.

This is for all those times when you are watching an important issue and you receive 6 emails in 5 minutes as various people make and save various changes to the same issue. Not everyone has gmail to combine those all for them.