An interesting registry key which not many people know about for the Enterprise Vault Outlook Add-in is theDeleteHiddenMsgBtnVisible setting.
When the key is added to
HKEY_CURRENT_USER \ Software \ KVS \ Enterprise Vault \ Client, and as a DWORD set to 1, then a new, hidden option is enabled.
This is the option to delete the hidden message, if found, on a folder by folder basis. It can often be done instead of ‘zapping’ the mailbox, which is something which is done all too often.
The reason for deleting the hidden message is that sometimes it gets out of synch between the end user in Outlook cached mode, versus the online copy of the hidden message (which is what Enterprise Vault writes to)
Here is the Vault Information dialog before the registry key is added: