A question arose the other day, which is worthwhile covering here. The question is :
When using Outlook 2007 or Outlook 2010 Instant Search, with Virtual Vault enabled, what is meant to be searched?
To answer this you need to consider what you are truly looking at within Outlook when you have Virtual Vault enabled. Virtual Vault for all intents and purposes is the MDC file, one file.. with “stub” information in it of all the items in your archive. Even if you have no vault cache content stored locally, or if you have size limitations, or date limitations, the MDC, the metadata, is always the complete set. It contains things like dates, times, subject, recipients, and most importantly the first 120 characters of the message.
When you search with Outlook Instant you have the following options (From Outlook 2010) :
All mail items
All Outlook Items
I have not seen any difference between All Mail Items and All Outlook Items, whenever I have done any testing with or without Virtual Vault and Vault Cache
So what you are searching is just that metadata, not the full content of the archived messages. For that you’ll currently need matching bitness of Windows and Office, and to use the Windows Desktop Search (WDS) interface.
The follow up question was whether we document this anywhere, and we do. See the reference at the bottom and in particular this section :
Important Note: Searching for archived items via Outlook "Instant Search" when using Virtual Vault is still an option with both Windows 32-bit and 64-bit. This will continue to operate successfully however search results will be based on archived item metadata only of the items in Vault Cache.