Ever since Eudora went kaput, I've been looking for a new email app that has even half the features I loved about that old workhorse. While the interface of Postbox isn't very Eudora-like, I've come to like tabbed browsing MUCH more than separate mailboxes, which was the Eudora-unique UI element I wanted most (and was the hardest thing to find). I'm a QA consultant by trade, so in the process of trying every available app under the sun (Entourage, Apple Mail, Thunderbird, Revolver, PowerMail, Correo, Gyaz, the T-bird based Eudora pretender called Penelope, the attempted Eudora replacement called MailForge, etc.), I created detailed QA worksheets for my finalists, and came down to two: Postbox and Outspring. I was leaning toward Outspring at first, but their communication with beta testers is almost non-existent, and their development slow. It wasn't long before Postbox's functionality passed Outspring's and now Postbox is a much stronger, more stable app with almost everything I want, plus a bunch of features I didn't know I needed until I had them: To-Dos - click one icon in the mailbox, and any email becomes pinned to the top of the mailbox so it doesn't end up "out of sight/out of mind." Conversation view - Gathers all emails in a given string and puts them in one viewing pane, with all the quoted text suppressed. Practical upshot: a VERY clean view of an entire conversation. Inspector pane - Incoming emails have a sidebar showing attachments, images and links, plus a bunch of simple, quick tools for finding other emails from the same sender, adding them to your addy book. Contact panels - Click on a sender's name, and you can see their Address Book info, perform instant searches, create a filter, etc. Multiple status states - the "read" column in the mailbox can be a blue dot (unread), a little clock (waiting, e.g. for a reply) or blank (read). Attachments tab - All my attachments in one place, without having to dig through User > Library folders. Images tab - All attached and inline images in one place: Trying to find the message you know had your nephew's school picture in it? Find the picture, and follow it to the email. Compose sidebar - I don't use this one much and it still needs some work (Postbox is in beta after all), but you can quickly access previous attachments and images, add signatures, look for maps to include, etc. Topics - didn't like these at first, but now I think they're far BETTER than colored text or highlighting of messages in your mailboxes, and you can have multiple topics per message. Plus there's a Favorite Topics section of the sidebar where you can look just at mail with a given topic. (Example: I can see all my mail labeled "politics" in one place, regardless of what folders I've put them in.) Tons of keyboard shortcuts - although they're not always intuitive (some require CMD, some don't) and there's no cheat sheet yet. Thunderbird Add-Ons - new in this release, and I'm really excited about being able to file messages with just a few keystrokes (instead of drag-and-drop) with the Nostalgy plug-in, for example. Editing - This is BIG one for me: You can edit received mail. Bold or color important passages, change the subject line to something that makes more sense to you, etc. Eudora had this, and just about no other app does. Plus very good search, a very attractive an easy UI, and a LOT of flexibility regarding how you handle your mail. Different in box for every account? Sure! Same in box for every account? You can do that too (can't do both though, like in Apple Mail — yet). There are a few things I wish were better. There's still no app out there that can compete with Eudora's fantastic filters, and Postbox can be slow to render at times. It could be easier to move mail between accounts (although Nostalgy fixes that too). And I really, really miss the "Who" column in Eudora mailboxes. It makes so much more sense than having to have "Sender" and "Recipient." OK, I've just realized how much I sound like an employee plant here. Not the case. In fact, I offered my QA services, but they've go it covered. However, now that I'm settled on Postbox, I do have an active interest in seeing it succeed so I don't have to go through again what I went through when Eudora died. So here I am, posting the longest VersionTracker review EVAR. Shutting up now, except to say that Postbox is extraordinarily stable for a beta.