Setup Outlook to connect to Exchange over HTTP
Installing the certificate
Navigate to servers webmail and install certificate.

Continue to the OWA.

Select the certificate by the top of the address bar and click view.

Note the address below, use this address for entering into the outlook configuration.
Click install
Run though the Certificate installation wizard using the default options.
Once the wizard has completed you will be presented with :

Double check the address and select yes
Setting up Outlook
Navigate through outlook or control panel to account settings, select ‘More Settings’, select the connection tab.

Select the ‘Connect to my Exchange mailbox using HTTP’ tick box under ‘Exchange over internet’ heading

Enter in the URL of the exchange server, this was noted above when the certificate was installed.
Select ok after entering in required information, select ok all the way back up the chain
Outlook access is now setup for use outside of a VPN