Perhaps someone will find this useful...
If you're using Outlook 2011 and when you search for messages they no longer show up in the search results --either you get "no results" or results that are most definitely wrong -- you can probably fix it by doing some combination of the following.
First, make sure Office 2011 is up to date. This won't actually affect the search problem, but there are enough other problems that it will fix that you should do it. As of writing this comment, the current version of Office 2011 is 14.2.4. You can get updates from Office's Auto Update, or by downloading them from Microsoft directly
A little background on how Outlook searches. Like Apple's Mail, Outlook uses Spotlight to search for messages. Anything that interferes with Spotlight searches will prevent Outlook from finding messages. That said, Outlook seems much more prone to problems finding messages than Apple Mail, which suggests that Outlook doesn't reliably handle the results returned from Spotlight. In other cases, Spotlight has no trouble finding messages that Outlook can't, so again I have to assume there are bugs between Outlook and Spotlight that are not solely limited to Spotlight itself.Solutions:
First check items 1 - 3, then perform step(s) 4 and/or 51.
If you have any old Outlook databases that you've rebuilt, try deleting them. They're in /Users/<yourname>/Documents/Microsoft User Data/Office 2011 Identities
. Old databases that have been rebuilt are in clearly labeled folders. If you need to keep any of these databases, either copy them to appropriate backup media or zip them before deleting them. That won't solve the problem, but the places I've seen failed searches most often is on systems where there are old databases that have been rebuilt, so killing them off seems like a good idea -- it's doesn't prove the problems are related, but there does seem to be a noticeable element of correlation.2.
Make sure that there are no Spotlight privacy settings blocking indexing of your Office 2011 Identities folder. To do so, open System Preferences and click Spotlight. In the Privacy tab, make sure your Outlook Identity is not listed, nor any folder above it, for example: Microsoft User Data; Documents; your User folder; or your hard drive. If any such folders are listed, remove them from the privacy list by clicking them and then clicking the [-] button.3.
Make sure Spotlight is configured to search for email messages. Again in System Preferences --> Spotlight under the Search Results tab, make sure there's a check next to Mail Messages (I think the name of this item is slightly different in OS X 10.7+). It would also probably be a good idea to put check marks next to Events and Contacts while you're at it (but I don't know for certain that Outlook searches its contacts and events using Spotlight -- it would just be a logical thing for Outlook to do).4.
With items 1-3 out of the way, if you have a relatively modest number of messages and they're all stored on IMAP accounts, you can delete the IMAP account and then re-add it. This will delete all the messages in Outlook then re-download them from your email server. DO THIS ONLY IF YOU HAVE YOUR MESSAGES STORED ON THE SERVER! When the messages are re-downloaded they'll be re-indexed and you should be able to search again.5.
If you have a large number of messages so that reloading them from your IMAP server will take too long, or if you're using POP3 rather than IMAP, or you otherwise have lots of messages stored only on your computer, or you're just nervous about it, try rebuilding the Spotlight index on your hard drive. This will probably take a couple hours on a typical computer, but could take longer. To do so, first quit Outlook then open the Terminal, type the following, and press return:sudo mdutil -E /
Type your computer password when prompted. After a minute or two you'll see a little dot start blinking in Spotlight's magnifying glass in the upper-right corner of the menu bar. That indicates the Spotlight index is being rebuilt. When it goes away, fire up Outlook again and see if you can search.
That combination should do it. Good luck...