How can I enable e-mail search functionality on volumes that are not indexable by Spotlight?

I observed that e-mail search functionality doesn't work, and the reason appears to be that Spotlight refuses to index this volume:

For the sake of reliability, I am very reluctant to move "$HOME/Documents" directory to, say, my local drive.  (My NAS is protected by RAID and is backed up regularly.  Moving critical data off of the NAS would complicate matters considerably.)  By the way, it's perfectly fine with me if exactly one host--the computer on which I'm running Microsoft Outlook--is responsible for indexing the drive.  In other words, I don't require or expect multiple Mac OS X hosts to be able to use Spotlight with this volume--just the one that is running Outlook.

Having one's e-mail in a network-mounted directory is an entirely reasonable use case, so I'm wondering:

1. Perhaps I've misconfigured my NFS server or the NFS client settings in Mac OS X, and with a tweak or two, Spotlight can be made to start indexing this internal drive.

2. Perhaps Microsoft offers an alternative way, that does not depend on Spotlight, to index and search through one's e-mail.

3. If neither #1 nor #2 is the case, how can I contact Microsoft to request that they add this feature to a subsequent release of Outlook?  Whether the deficiency is in Spotlight, Darwin, Mac OS X, or Microsoft Outlook, Outlook really ought to be able to cope with such a use case as this.  Not being able to search e-mail on a network-mounted volume is unacceptable.

Where do I go from here?