OpenDNS or other DNS services may Interfere with autodiscover
When using OpenDNS or similar services you may experience a certificate error during the autodiscover process. This certificate error is caused by the way that some of these services handle autodiscover requests. Outlook will be unable to properly resolve the autodiscover SRV record due to the typo correction and domain redirection features offered by these services.
It is recommended that you disable any domain redirection or typo correction DNS services before proceeding with Outlook autodiscover configurations.
As an example, here is the certificate error you will encounter when using OpenDNS with typo correction and/or domain redirection enabled: