I've become quite a fan of Apple's Mail.app over the last few years, but the need for better OpenPGP support and more flexible templating options moved me to try Thunderbird again recently.
The last time I tried using Thunderbird (a year or more ago, on a Linux machine at the time) it was quite a buggy beta. The UI would freeze while it tried to connect to the mail server, and was generally a nightmare responsewise. Anyway, I decided to check it out again. Installing the latest Thunderbird release on OS X was a breeze, and I immediately got to work using it to clear out my ToDo queue. After a bit of Real Work™, I had the inevitable urge to kill some time by compiling an at-first-sight pros and cons list for Thunderbird. So here goes...
- Open source, multi-platform.
- Much more comprehensive OpenPGP support with Enigmail.
- Enigmail doesn't get confused by signatures that cover only part of a mail.
- Enigmail supports smart cards, photo IDs, keyservers, key management.
- Flexible templating mechanism with Quicktext.
- Snappier, more responsive than Mail.app.
- RSS, Usenet support integrated.
- IMAP IDLE support. Messages show up in Thunderbird right away!
- Labels support.
- Ability to 'narrow' message list based on various criteria.
- Saved search folders.
It seemed at first that the pros outweighed the cons. The ability to use the same program on OS X, Linux and Windows is very handy. It's also great that it's an open source program, therefore much more hackable by just about anyone. And it sure seemed to surpass Mail.app in terms of bleeding edge features.
- Non-emacs keybindings in the message editor! :-(
- Less intuitive configuration and menu layouts.
- Filters don't seem to work right.
- I didn't see a way to search in all folders at once.
- No built-in signature/template support (but see Quicktext).
- Crashes often and early.
A Second Opinion
After using it a bit more, I'm more than a little disappointed with Thunderbird's stability (on OS X). Sure it's a lot faster than Mail.app, but it seems to be doing a lot more interactive IMAP stuff than Mail.app did, and frequently needs to be restarted after it gets into some weird error mode.
The lack of an activity window like Mail.app's makes it difficult for the user to see which email connection is causing slowdowns.
I still haven't got the hang of the RSS subsystem. It flattened out the OPML file I gave it to import. And when I move feeds into new folders after creating them, it becomes impossible to edit that feed's properties (URL, etc.) thereafter. Quite a bummer.
Nevertheless the speed improvement over Mail.app has me hooked (so far). The Quicktext plugin gets a lot of the credit for this, as it is way more flexible for templates and frequent phrases that Mail.app's signatures (which can be used for the same purpose, though not as effectively).
So for now I'll put up with the frequent restarts and hope Thunderbird stabilizes in a few more releases.
Prologue: Back to Mail.app
OK, so Thunderbird managed to delete a lot of my recent mail. Luckily, Mail.app had cached a copy of most of the messages. I'm also quite sick of Thunderbird's frequent crashes, horrible search, flaky filters, and general instability. I'm switching back to Mail.app!
Sure, Thunderbird has all the bleeding edge bells and whistles, but none of the features work trouble-free, not even basic, core functionality. In the final analysis a mail program that works reliably at what it does is way more useful than one which has all the latest features, but nothing works.
I've also dropped Thunderbird on Linux in favor of Evolution, which is much more responsive (and has OpenPGP support built-in), and of-course I long ago ditched Firefox for Galeon, which has been the best web browser around for quite a while (gotta love the save-state-on-crash feature!)
I found the OS X version of Evolution thoroughly unusable, though. It's extremely sluggish, takes ages to display a message after you select one, and lags far behind Mail.app in terms of finish and general usability.
In the final analysis Apple's Mail.app is still probably the most reliable, responsive, usable and full-featured email program available for OS X, or any platform for that matter.