If you have been using an SSL Certificate to secure internal domains for your Exchange deployment such as the Client Access Server's internal FQDN (e.g.
So Microsoft Exchange File Distribution Service is removed from the CAS role.
I am trying to explain the conventional methods for forcing the OAB generation in Exchange 2013 and fresh download on an Outlook 2013 environment.
Replace Your Certificates for Internal Names – Part II.
To update your Exchange 2007, Exchange 2010, or Exchange 2013 server you will need to run the following commands from the Exchange Management Shell and replace the Server running the Client Access Role with your external domain name.
If you are on a personal connection, like at home, you can run an anti-virus scan on your device to make sure it is not infected with malware.