Users may not be able to open full messages from Virtual Vault by double-clicking the item when the reading pane is enabled. This will occur if the "VVReadingPaneContent" desktop policy is set to either "Never show content", or "When in Vault Cache" and the item is not in the content cache.
The stub message is opened instead.
If the Outlook reading pane is turned off the full message will be opened regardless of the "VVReadingPaneContent" policy.
This issue has been addressed as part of the following release:
Enterprise Vault 9.0.3 - Release Details
Enterprise Vault 10.0.1 - Release Details
The Outlook reading pane is enabled
VVReadingPaneContent desktop policy set to "Never show content" or VVReadingPaneContent desktop policy set to "When in Vault Cache" AND the item is not in the content cache.