I am having the same issue.  I tried to add myself to the list of affected users as per the recommendation in this thread.  The person I chatted with told me that Outlook will not longer be used and that the issue is with Outlook and they can't help me and that our only option is to use webmail.  I hope that is not the case as we use Outlook for tracking responses to these email messages and for other reasons as may professional businesses do.  NOT HAPPY!!!