By default, each time you add a new Clipp to a collaborative Clippboard, all collaborators on that Clippboard will receive an email and a notification on Clipparoo that there is a new Clipp. If you do not want to send an email out for a particular Clipp, uncheck the Email Collaborators checkbox that will appear above the Save this Clipp button while creating your Clipp. (Your collaborators will still see a notification on their Clipparoo page even if you uncheck the email box.)
You'll receive a notification on your Clipparoo homepage whenever a new Clipp is added to one of your collaborative Clippboards. The person creating the Clipp can choose whether you will also receive an email.