User is allowed to set an email as a notification email even without verifying the new email in all previous GitLab CE/EE versions through 13.0.1
https://hackerone.com/reports/471907
https://gitlab.com/gitlab-org/gitlab/-/issues/25994
https://gitlab.com/gitlab-org/cves/-/blob/master/2020/CVE-2020-13276.json