I'm guessing that you'd sooner not change all your process notifications to prevent this? By far the easiest way would be to set all your End Users to have 'Internal Only' notifications so if anything is generated to be sent to them it won't get sent via email. You can do this quite easily with a script:
UPDATE tps_user SET tps_notify_method = 1
WHERE tps_user_type_guid = (SELECT tps_guid FROM tps_user_type WHERE tps_name = 'EndUser')
to reverse this for go-live you'll need to set the tps_notify_method to 2 for these users. If you want to turn notifciations on/off for other user types change 'EndUser' to 'AccountManager', 'Contact' or 'Analyst'.
I will try your script. Thanks for also providing the reversal for when we Go Live.