How can I find out if group members on our Gitlab.com group signed up with their corporate email?

My company has a large group on gitlab.com, we’ve been making an effort to ensure that people have been signing up with their corporate email account and not using personal Gitlab accounts (for security reasons).

I need to be able to audit the group members to make sure that this is the case for everyone, however:

  • Email is not listed on the members page
  • The Gitlab API only allows access to user emails by admins, and obviously I’m not an admin of gitlab.com

How can I audit our group members, short of removing every one of them and re-adding?