Mail’s Spotlight-based search feature stands up reasonably well to heavy use, but as your e-mail archives begin to swell, Mac OS X’s indexing can’t quite keep up—the bigger your Mail archives, the slower Spotlight searches in Mail become.

Enter Rocketbox, a new plug-in for Mail that augments Mail’s search capabilities and claims to increase the speed of searches by up to 200 times. While that claim may be optimistic, Rocketbox does give you search capabilities Mail can't match on its own.

The first time you launch Mail after installing Rocketbox, Rocketbox indexes your Mail archives. The length of the process depends on how many messages you have in Mail: In our testing, it took nearly half an hour to index just over 50,000 messages across three different e-mail accounts. Once indexing is complete, your Mail searches—whether you initiate them in Mail’s Search field or in the optional Rocketbox window—are handled by Rocketbox.

(One difference you’ll notice immediately is that unlike Mail’s stock search, which begins displaying results as you’re typing, Rocketbox doesn’t show results until you finish entering your search term and press Return; doing so opens the Rocketbox window to display the results.)

Rocketbox offers a number of nifty search enhancements. For example, begin typing the first name of any person with whom you’ve previously corresponded, and Rocketbox’s suggestion menu displays matching names; select one to display any messages to or from that person. Unfortunately, this feature works only with first names; it doesn’t work with last names or e-mail addresses.

Rocketbox also supports a host of search syntaxes, boolean operators, and wildcards, and it allows you to group the various syntaxes together to perform very specific searches. As an example on the Central Atomics Website demonstrates, typing “from:matt AND cc:bob AND subject:”Dog food”” will bring up only the e-mails about dog food sent to both you and Bob by Matt.

Rocketbox’s results window is especially useful, as it shows relevant excerpts of matching messages, highlighting the terms you searched for. You can filter the results by time (the past week, past month, and so on) or folder(s), or display only messages with attachments or that have been forwarded, flagged, or replied to. You can also sort the results by relevance or date.

Interestingly, in our testing Rocketbox often seemed to return more results than Mail’s built-in search, although in some cases Rocketbox’s results seemed to include the same message more than once.

As for performance, Rocketbox is plenty speedy, always displaying search results nearly instantaneously. Does it live up to the “200 times faster” promise? In switching back and forth between Rocketbox and Mail’s own search, neither consistently returned faster results than the other. However, Mail begins searching as you type and displays results as it finds them, which can result in slower look-up speeds. Rocketbox doesn’t begin searching until you press Return and displays only the first 20 results—to see more, you have to click on the Load More Results button—so it “feels” as though you see results more quickly.

One feature we’d like to see is the capability to search within message attachments, given that Mail’s own search feature can do this. To its credit, Rocketbox allows you to switch to Mail’s built-in search if you ever need to do so. Rocketbox also currently lacks a number of other features you get with Mail’s built-in search; for example, you can’t save a search as a Smart Folder, you can’t perform actions (replying, forwarding, deleting, and so on) on messages in Rocketbox’s search results, and you don’t get a list view. However, many of these features are in the works, along with several others, such MailTags integration and an improved search field.

(Note that there are two different versions of Rocketbox: one for Snow Leopard [OS X 10.6] and one for Leopard [OS X 10.5]. Be sure to download the correct version for your version of Mac OS X.)

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