Enterprise Vault™ Configuring Internal and External WebApp URLs for OWA

Using an Exchange CAS proxy

The main difference with using an Exchange CAS proxy is that it is the proxy server which determines whether to use an external URL, and not the Exchange CAS actually processing the requests.

In this example, the same URL, https://owa.company.com/owa, is used for both external and internal access to OWA. The Exchange CAS in site A acts as a proxy server and forwards requests to the Exchange CAS in site B. This means that to the Exchange CAS in site B the originator of the request appears to be the first Exchange CAS. For this reason it cannot determine whether the request has come from the Internet or from an internal client in site A.

The following settings should be used:

External Web Application URL: <https>/enterprisevault

EntepriseVault_ExternalIPAddresses: 192.168.0.21. Note that this is set on the Exchange CAS in Site A.

If the Exchange CAS in site A determines that an external URL should be used, then the first Exchange CAS appends an extra query string parameter to the request passed to the Exchange CAS in site B. This allows the OWA extensions doing the real work on the Exchange CAS in site B to use an external URL if necessary.

The Exchange CAS in site B has no additional configuration to determine whether to use external URLs, as it does not handle external requests directly. Hence requests from the internal client in site B will always use the internal URL.