Microsoft has introduced an update for certain Office products that can cause users to see issues in their Outlook client including username/password errors, unexpected From addresses appearing in their outbound email, or Autodiscover certificate errors.
The attached patch below will restrict Outlook's Autodiscover lookup method to prevent Outlook from autoconfiguring Outlook.com accounts and Office license associated addresses. The patch will also provide a slight speed increase during the Autodiscover lookup process. We recommend applying the patch to the registry of any PC running Outlook 2013.