We recently renewed our SSL certificates for Exchange 2013 and ran into errors that were related to having a domain.local account on the certificate, as they will no longer be supported. We believe we managed to fix these issues since new Outlook profiles that are created (or re-created) no longer result in proxy server security certificate error or the name on the certificate being invalid.
However, existing profiles still display these errors when opening up Outlook. I'm trying to figure out a good way to resolve this for 100+ users without needing to recreate profiles. I tried to delete the .ost file, but, while that prevented the proxy error from showing up, it still seemed to give the name on the certificate error.