It would be good to have a global sandbox mode, when ticked a fixed CSS asset would show along the bottom of the website saying in sandbox mode.
The global sandbox mode could override all other sandbox modes for payment etc.
When in sandbox mode there would be a checkbox to 'send email' or not to. When testing bulk imports from ebay/amazon etc we do not want to send thankyou emails to thousands of people :)
Vote here if this would interest you.
