It started with a bug in WordPress 2.2 that meant not only edits to a page triggered an update to be sent but also a new comment being left. If you left the ’send email notification to subscribers’ toggled on, some unwanted email was being sent. So it was time to re-write it.
The big news is that it now works with Posts. It amazes me that anyone would want it to but yes - I have been asked for this so often I have now supplied it. And the method of marking a change for update emails to be sent is now simply made in the actual Write Post and Write page screens with a simple little checkbox!
For ful details: Post/Page Update Notification Plugin Page