Pete,
what you're asking for is available already.
I admit it's not obvious and tucked away, but you can find what you asked for here:
Email on Motion Settings "Send email when camera does not work"
This option is available once you store locally or with FTP upload.
As far as I remember it is also working if you don't use motion detection, but either local save or ftp upload must be active. The configuration exists for both ftp upload and local save independantly.
(also, SelfCheck does check the camera and restarts it when a problem occurs - I wonder why this did not do the job. Do you have a debug log?)
