If the other Spotlight fixes don't work, you might need to reset your entire Spotlight index, although rebuilding it will take quite a bit of time--many hours if you've got a large hard drive full of files. In Terminal, enter this command and then press Return: sudo mdutil -E / Enter your OS X account password when prompted. (Note that only an account with administrative access can use this command.)

A final possibility, which again applies only to server-based accounts, is that the messages in one or more mailboxes weren't downloaded correctly or completely in the first place. To fix this, first choose Mailbox -> Synchronize to make sure server-based accounts are updated. Give Mail some time to process--you can view Mail's Activity window, via Window -> Activity, to monitor progress--and then try your search again.

If that doesn't work, select each mailbox containing messages that aren't being searched properly, and then choose Mailbox -> Rebuild. This erases the local copies of all the messages in that mailbox and forces Mail to download them again from the server. In some situations, this can take even longer than rebuilding your Spotlight index, but it may be the only way to fix certain mailbox problems.

Senior contributor Joe Kissell is the senior editor of TidBits and the author of the ebook .