Provide an option for user to turn notification on/off

Currently, if i am watching a space, i will receive email notifications when someone creates or upload any attachments.
This creates a email spam unnecessary. It should be coupled with a default turn off (via checkbox) when the page has been edited by the same person. Otherwise there will also be email notifications when a user tries to save in order to preview.

The page history should also be able to be compressed thus reducing on the number of unnecessary versions.