Scenario: When accessing Outlook Web in Exchange Online, a user is redirected to a CAPTCHA page asking to ‘Verify your account’. However the Captcha test never fully loads and you are unable to verify to access your mailbox in Outlook Web — it appears stuck.
Solution: Quickly, navigate to https://outlook.office.com/mail/options/calendar/calAccounts and remove any accounts that you may have connected to previously. It was a race before being redirected to the Captcha site. We had a user with a GMAIL account configured, and after removing it the use was unable to access Outlook Web. The user can access Gmail on Gmails site ;).
Ex-Shell 