If the user account is blocked from accessing O365 with this message;


To unblock;

  1. Reset user password
  2. Login to 365 Admin
  3. Open Azure AD Admin page
  4. New layout: Protect and Secure - Risky Activities - Risky Users
  5. Filter for username
  6. Select user
  7. From 3 dot menu select 'Dismiss User Risk'