Get email from twitter OAuth2

Twitter's new Oauth 2.0 user authentication does not currently (at the time of writing this answer) provide access to the user's email address, and will require an additional scope to be added. This is on the Twitter API roadmap and is a known feature request.

You can still use OAuth 1.0A and set the option to request the user's email address.

The solution was found in the twitter developers dashboard.

First of all go to the settings of your app.

Then you have to fill in a link to your privacy policy & terms page.

After that also enable OAuth 1.0 en then an option pops up to also receive the email address from the user that is trying to log in.