For some reason, auto discover is failing for outlook 2007 only. Auto-discover works fine for the users with outlook 2010 and 2013. We have combed through every possible setting that could be affecting this. The auto discover and mail DNS records are point to the correct server. We have gone through IIS, and verified correct links. We have rebuilt the EWS directory. When running the outlook Email test auto configuration, it fails every attempt to pull in auto discover settings. If you need additional information, just let us know and we will be happy to post.