I've been using Eudora for the past ten-plus years, and it's mostly been very good to me during that time. I like the multi-window model (and not only because it makes people flee in horror when they see how many windows I've got on my screen); I like the very fast search; I like the ability to instantly sort a large mailbox by any of several columns, and to instantly cluster together all the messages with the same subject line or the same sender or whatever; I like the fairly powerful mail-filtering system; I mostly like the labeling system. I also use Eudora for note-taking sometimes, because although DEVONthink Pro is lovely, it still doesn't feel quite as lightweight as Eudora for just jotting down a few quick notes.
Unfortunately, there are also some downsides. One is that Eudora for Mac hasn't had a serious upgrade in years. It doesn't handle HTML email well, and it's pretty bad at dealing with non-ASCII character sets.
But the biggest downside has to do with the way it stores messages. A mailbox is a single file containing all the messages in the mailbox. That's not so bad (though it does prevent me from using Spotlight to index my mail files), but what's less great is that Eudora keeps track of where the message boundaries in the text file are using a resource in the file's resource fork. If you don't know what that means, it doesn't matter.
The problem comes when a mailbox file gets corrupted. If something goes wrong while a mailbox file is being saved, then the "TOC" data that keeps track of where each message starts can get out of sync with the actual messages. This leads to severe data corruption, especially if you accidentally re-sort the messages before you realize there's a problem.
What's really unfortunate is that sometimes Eudora just hangs or crashes. It's happened half a dozen times to me in the past few months that midway through checking mail, something will go wrong, and the only way out is to force-quit. Which leaves mailboxes in indeterminate states. Which has the potential for major data corruption.
When that happens, the only fix I know of is to open any corrupted mailboxes in Rezilla (or ResEdit, on older versions of MacOS) and delete the TOC resources, so that when Eudora next opens the mailbox, it'll have to rebuild the TOC by examining where the message boundaries actually are. That works fine, but it means you also lose metadata about whether you've read and/or responded to each message, which is info that I totally rely on. So I end up having to reconstruct mailboxes based on a combination of the corrupted original, a backup, and the corrupted version with a restored TOC. It's a time-consuming and failure-prone process. But I haven't run into the hang-during-email-check problem in a couple of weeks.
And then last night I was on my way to bed, and I decided to compact my saved-outgoing-email mailbox. Compacting Eudora mailboxes regularly is a good idea, usually; it usually minimizes the damage that can result if the above sorts of things go wrong.
Except this time, something went wrong during compaction. Eudora told me that it had encountered an unexpected end-of-file, and it immediately closed the mailbox. I reopened it and everything looked okay at first, but when I looked closer (using a text editor), I realized that something had gone seriously wrong.
The last backup I had was two weeks old, from just before I left for Chicago. After much shuffling of files, I managed to reconstruct almost everything; I ended up losing only 11 messages, half of which were to mailing lists or aliases that I'm on so I have other copies of those.
The only really unfortunate thing I lost is due to the fact that when I have a bunch of browser windows open, I copy the URLs and brief descriptions into a blank email for later posting as a journal entry. (I have dozens, maybe even hundreds, of these sets of URLs lying around waiting for me to get around to post them. Most of them will never be posted.) I just did that the other night, listing two or three dozen URLs with all sorts of neat stuff that I wanted to tell y'all about. But that whole message completely disappeared. I could reconstruct a few of the URLs via my browser history, but it would be time-consuming and very incomplete, so I think I won't bother.
This is just the latest in a long string of recent technology failures. I would recommend that y'all go run backups, except that at least one of the recent technology failures involved a backup failing. But, yeah, go back up your important data anyway.
Feh. I want technology to work better! I keep hoping that when Leopard ships, Apple's new "Time Machine" technology will resolve a lot of my lost-data problems, but I imagine there'll still be plenty of room for failure.
I also want better email software, but that's a different rant for another time.