Disable email response to Ideas submitted Merged

I would like the ability to disable the automated emails that get sent in through an Idea submission form. There are currently two emails that get sent - one as a "thank you for submitting your idea",and then additional emails when the Idea's status has been changed. I'd like the ability to disable 1 or both types of emails. The second is particularly important to disable when the user does not have access to view the ideas in a portal (I'm creating a "submit only" portal). In this case, if they were to receive an email that the status has been updated it would be meaningless because they don't have a way to go back and track that idea in the portal.