Alot has been written about Windows Search and how it works, or not, with Enterprise Vault. The main issue comes about because you can get into a mixed bitness configuration. By that I mean Windows 7 64 bit, with Office 2010 32 bit. This causes problems.
Outlook Instant Search - What does it search?
Outlook Instant Search only ever searches the Enterprise Vault Virtual Vault Metadata cache. This is on top of Outlook items. The Enterprise Vault metadata that can be searched using Instant Search is things like the date, author, recipients, subject, and up to 120 characters of the message body. This therefore excludes things like the full body content, and excludes attachments.
How can I search full content?