Thunderbird: An Open Source Email Client

When I switched away from late last year, what I switched to was Thunderbird. Overall, I’ve been very happy with it. I love the fact that I can use Thunderbird from both my Mac laptop and my Ubuntu desktop. I wish I could share address books between the two, but I’ll probably eventually resolve this by setting up a central LDAP server for myself.

Thunderbird comes with a pretty basic feature set, but allows additions via downloaded extensions. (Thanks to Beck for the comment on my previous post about adding keyboard short cuts to Thunderbird with Nostalgy. I really like it!) I suspect that many of the more advanced email handling features I want could be developed as Thunderbird extensions. Unfortunately, it seems that most of the really cool extension development efforts are going to Firefox extensions instead.

My biggest irritation with Thunderbird is in message caching and offline access. It does have a “work offline” feature, and I like the fact that when I explicitly tell it to go offline, it offers to download all my email first. Offline access to messages works fine for my IMAP inboxes, but it doesn’t cache my IMAP folders (even if I’ve explicitly selected them for offline use in my settings), so when I click on messages in folders all I get is a polite notice that the message wasn’t downloaded. This makes it difficult to clean out my Parrot mailing list folder while I’m on the train, for example, something I used to do all the time in

If I don’t explicitly set offline status when I go off the network, Thunderbird gives me “Failed to connect” dialog boxes every time I click on a message or folder, or try to send a message, and sometimes just gives me random connection error dialogs when I’m not doing anything. I get around it by setting offline status, but it’s unnecessarily disruptive. handles a lost network connection much more gracefully, only warning me when I try to retrieve new mail. I also wish Thunderbird would queue up messages to send later anytime the connection fails, instead of only when I’ve set offline status.

I also have problems with Thunderbird’s searching capabilities. Searching by To or From address or message subject always works beautifully. Searching message bodies (the “Entire Message” feature) is unreliable. I can copy a string out of a message, search for that string and get no results, then come back 10 minutes later and do the same search and get 50 results. It’s also slow. I can’t complain too much about that, since I’m searching an IMAP inbox with ~3,000 messages, but manages a much faster search over the same IMAP inbox for the same string. I suspect the explanation lies in Thunderbird’s caching problems, as sometimes it gives me a timeout error from my IMAP server in the middle of a 2+ minute search. It really shouldn’t be doing searches on the IMAP server but on the local cached copies.

Thunderbird is also getting quite slow in general lately, as my mail folders grow. I suspect this is the caching problem again. Deleting a message from an IMAP inbox can take 30 seconds to a minute in Thunderbird. Deleting a message from the same IMAP inbox in takes less than a second. I can probably work around this (and still have access from multiple different clients) by setting up an archive IMAP server (that can be slow and carry a large number of messages), while keeping my primary IMAP mail accounts light and empty. This is why I was trying out the Pair account, and also why I want the “automatically archive after 30 days” feature. (Thunderbird currently only offers “automatically delete after 30 days”.) But, I really shouldn’t have to work around the limitations of my email client, it should work around my limitations as a human.

My annoyances with Thunderbird are relatively minor. But they’re a low level of constant irritation, like water dripping from a leaky faucet. Lately I’ve started looking for other options. At the same time, with a tiny bit of usability polish and a few more advanced extensions, I could imagine being a loyal Thunderbird user for many years.