Canvas graded survey sending out emails

Every students that finishes a graded survey automatically gets an email saying that their survey has been graded. This is disruptive and we need to turn off this feature. As this is the only way "realiable" way of getting essayquestions through the api we need to be able to automatially get all answers and generate the data off them.

So the questions is, how can we turn off the automatic email? I see nowwhere a setting to change this.