Since password  management is done in Active Directory, you would have to
write a custom app to periodically poll AD with the users  you're looking for
and then send those alerts out as a timed event or something.

You could tie into SharePoint in order to filter the user list down but it's
generally an AD thing here and has very little to do with SharePoint (also
the email address is stored in AD so you would probably use it for sending
out emails directly).