It might take up to 24 hours for this change to take effect across all services. Be sure to tell the user about this change. ...

It might take up to 24 hours for this change to take effect across all services. Be sure to tell the user about this change. They will be prompted to sign in with their updated user ID. If they use %BRAND_LYNC_ONLINE_SHORT%, they have to reschedule any %BRAND_LYNC_ONLINE_SHORT% meetings and tell their external contacts to update the old contact. After the udpate, the user will sign in to %BRAND_OFFICE_365_SHORT% using the new user ID. The password will stay the same.  User will also have a new email address, but the old one still works so no email will be lost.