If Apple’s Mail ( ) is the affordable hatchback of e-mail clients, Postbox 2 is the category’s luxury sedan. Handsomely appointed with why-didn’t-anyone-think-of-this-sooner features, Postbox seems to anticipate and serve your every e-mail need. The handful of bumps I encountered while taking Postbox 2 for a spin were more than balanced by how much fun it was to use.

The first time you launch Postbox 2, you’re automatically invited to import settings from an existing e-mail program, or set up an account by entering your e-mail address and password. Postbox supports POP and IMAP accounts, but can’t work natively with Exchange servers.

Postbox spent several minutes importing more than 20,000 messages from Apple Mail, tying up much of my computer’s horsepower, but the resulting import included all my folders and files. A handful of garbled message fragments did pop up throughout my folders afterward, but they were only duplicates of existing, undamaged messages. The Postbox team is aware of the issue, and working to fix it in future versions.

Apart from its slick tabbed interface, Postbox looks much like every other e-mail client for the Mac, but its differences quickly become apparent once you start using it. Its improved Conversations feature leapfrogs both Mail and Microsoft Outlook 2011 ( ) in usefulness, displaying chains of e-mails in a single viewing window. Unlike Outlook, you can expand and collapse each message in the conversation, rather than having to click into and out of each individual message. You can even see neatly organized summaries of previous messages in a thread, complete with senders’ names and user icons, when replying or forwarding, rather than weighing down your message with a sprawling collection of increasingly illegible nested back-and-forths.

In other new or expanded features, Account Groups let you collect and manage different sets of accounts; one for all your personal mail, and another for all your business-related accounts, for example. A new Quick Reply box reminiscent of Google’s Gmail offers a no-frills way to swiftly dash off a response to a selected message.

New shortcut keys help you change mailboxes, or file messages, straight from the keyboard. Type G to switch mailboxes or V to file, start typing the name of the mailbox you want, hit return, and voilà! It’s fast, easy, and works like a charm.

Overwhelmed by a wall of indistinguishable messages in your Inbox? The new Focus Pane filters messages by attachment, user-assigned topic, date range, or one of a customizable list of your favorite contacts. View buttons at the top of the Postbox window work similarly, quickly displaying all the messages, To-Do items, attachments, or images within a selected folder.

Those views can all be scoured via Postbox’s excellent search feature. Use the search box at the upper right of the window, or click the adjacent search button for more precise searching by From, To, Subject, message contents, and more. Searches are fast and admirably accurate, though you’ll need to make sure Postbox has indexed your messages first. If those messages are stored locally, Postbox can zip through them in a few minutes; if you get mail via IMAP, Postbox will need to download all of those messages first, which took more than an hour in my case.

One of my favorite Postbox features is the Message Inspector, a sidebar that appears as you read messages. Here, Postbox gathers all the attached files, images, and even the Web links within the message in one handy location, rather than forcing you to scroll up and down through the body to find them. A similar feature when composing messages allows you to search for images, attachments, and contacts without leaving the new message window. Postbox won’t display PDF files within the body of the message, as Mail does, but it handles inline photos just fine.

Postbox 2 is built on Mozilla’s Thunderbird framework, which allows users to extend the program with free, downloadable add-ons. Despite those open-source roots, it also does a terrific job integrating with both the Mac OS and social media. You can preview attachments and images with Quick Look, send attached photos straight to your iPhoto library, search messages with Spotlight, and automatically add contacts created within Postbox to your Address Book.

After a simple setup, you can also post to Facebook, Twitter, and FriendFeed from within Postbox. The program will pull user icons for your contacts not only from the Address Book, but also from Facebook or Twitter accounts where applicable.

Overall, I found Postbox 2 highly intuitive and easy to grasp, with a well-written online manual and extensive help forums.

Macworld’s buying advice

If you’d like a top-notch upgrade to your e-mail experience at a reasonable price, and you can live without Exchange support, the terrific and thoughtful features built into Postbox definitely deserve your consideration.

[Nathan Alderman is a writer, editor, and conversation starter in Alexandria, Va.]