When using forms-based authentication, OWA 2003 and OWA 2007 client users are prompted to re-enter login credentials when starting Enterprise Vault Search, Archive Explorer, or first opening an archived item using Enterprise Vault View mode. This is because the request accesses a different IIS virtual directory (OWA 2003) or web server (OWA 2007) which requires different authentication.

View mode can be set to Enterprise Vault in the OWA settings on the Advanced page of the Exchange Desktop policy. This setting controls what happens when a user clicks Open the original item in the banner of a custom shortcut. If OWA is set as the value of this setting, then the original item is rendered by OWA (and looks like an OWA message). If Enterprise Vault is set as the value, then the item is rendered by Enterprise Vault.