Rocketbox

Rocketbox is a powerful, new way of searching your e-mail in Apple Mail.app. It's never been faster or easier to find what you need.

• Search by person - Rocketbox provides intelligent search-by-person suggestions, making it easy to see your e-mail correspondence with a person. Rocketbox's engine analyzes your e-mail correspondence providing a list of important contacts when you search.
• Powerful filters to handle lots of e-mail - Powerful filters make it easy to deal with lots of e-mail. Filter by time, person, folder, account and more.
• Inline search previews - Inline previews show you exactly why a messages was found, making it easier to find what you need. The highlighted sections help you improve your queries and takes the guess work out of using search.
• Advanced search support - Rocketbox supports a sophisticated and powerful query language for more advanced users.
• Save time managing e-mail - Spend less time manually filing messages and instead use search to find what you need.

Limitations:

Full version for 30 days