Facebook has been rolling out a series of changes to its platform that are all aimed at closing up loopholes following the Cambridge Analytica data breach. Now, the social media giant will be launching a certification tool that will check and ensure that marketers are only sending ads to email addresses that were rightfully obtained with user consent.

The tool is called the Custom Audiences certification tool. A Facebook rep wrote about the tool to a marketing client in a message spotted by TechCrunch. They wrote, “Advertisers will be required to represent and warrant that proper user consent has been obtained for the use of any data uploaded.”

Facebook is also going to prevent Custom Audience data from being shared across Business accounts, according to an anonymous email with the contacts redacted. Facebook confirmed to The Verge that the tool was being built and that it would require advertisers and digital agencies to certify they have permission to use user data.

Last week, Facebook announced it put a pause on app reviewing so that new apps could not join its platform. All of these changes are in response to the revelation in March that the data analytics company Cambridge Analytica had used third-party app “thisisyourdigitallife” to obtain and misuse user data from up to 50 million Facebook accounts. Facebook is currently being investigated by attorneys general from New York and Massachusetts for its actions during the period of the data breach.

Update April 2nd, 4:40PM ET: This article has been updated with Facebook’s confirmation the tool exists.