If you're in the market for a new email client to try, I mentioned Postbox a few weeks ago. Late yesterday, the Postbox team released beta 8, which features an improved conversation view, and new and improved support for QuickLook, Flickr, Hotmail, and Growl.

The beta also fixes many bugs found by users (including myself) and performance enhancements. Also, Postbox is heeding user suggestions to become more Mac-like, including keyboard shortcuts in menus, improved notification for unread messages in the dock, and the aforementioned QuickLook and Growl integration. Full release notes are available on the Postbox website.

Performance appears to be about the same -- which is to say pretty good -- and indexing on my 2006-vintage black MacBook still occasionally ramps the fans up to hurricane strength. I've been using Postbox as my primary email client for about three weeks, and its held up to my demanding workflow, but still has a ways to go before it becomes the killer email app.

Still, if you're a high-volume email consumer, Postbox is a solid option for you. Postbox is free (and will continue to be free, so far as we know), universal binary, and requires Mac OS X 10.4 or higher.

Postbox, the email client built for heavy email users, entered Public Beta on Sunday. Postbox is designed to allow you to search, organize, and manage your email more more efficiently.

Postbox includes a powerful search tool that lets you use Gmail-style search terms (like "from:Steve" or "before August 2008") to easily find messages. The Gmail-like features don't end there: Postbox automatically organizes threaded emails by subject. Messages can be tagged with one or more topics for easy recall later.

Perhaps Postbox's greatest feature is its ability to recognize what's in your email, and keep it front-and-center. For instance, if you're composing a new message, you can use the Compose sidebar to find attachments in other messages to drag into your new message. The inspector panel on the preview window highlights links, addresses and attachments in the message so you can get to them easily.

For me, I use my inbox like a to-do list. Thankfully, Postbox has a built-in Archive utility that lets you specify an archive folder for each account (which I already had set up). Once you're done with a message, clicking Archive or pressing A moves that message (or many messages) right into your archive.

Add to this to-dos, integrated search, social network integration, message annotation, tabbed browsing, and a high-security Mozilla foundation, and you've got an amazing Swiss Army-knife tool for hard-core emailers.