The state of the desktop email client Thunderbird
Thunderbird's usage continues to grow according to Mozilla despite the fact that the desktop email client has been put on the backburner by the organization in mid-2012.
Kent James, who is serving the chair of the Thunderbird Council currently, detailed in a blog post on Friday that Thunderbird usage continues to expand.
Program usage is measured by active daily installations (adi) based on pings Mozilla receives to the plugin blocklist that it maintains.
While Thunderbird does not make use of plugins, it is connected to the blocklist just like Firefox and other Mozilla programs are to provide Mozilla with options to block undesirable or outright malicious plugins and extensions from being run on customer systems.
The graph shows a rise from an average of 4 million peak pings per month in 2008 to more than 9 million in January 2015.
Back in mid-2012 when Mozilla made the announcement, usage was at about 8 million at peak.
James notes that the numbers don't reflect the total number of users of the email client. Users may not use the email client every day and pings may be blocked in computer networks or by users who don't want them to go out in first place.
It is clear that adoption has slowed down somewhat after Mozilla's decision to put Thunderbird development on the backburner as this meant less new features and exposure for the program.
Other factors must have certainly played a role as well including the ongoing rise of smartphones, the unbroken popularity of web-based email services, and a move towards apps in general as opposed to dedicated desktop programs.
The next big release will be Thunderbird 38 which will be released on May 11, 2015. It will incorporate the Lightning add-on as mentioned earlier. According to James, an option to not install Lightning on first start after the update is provided so that Thunderbird users who don't require it can block the installation from commencing.
While Lightning is without doubt the core new feature in Thunderbird 38, additional changes are planned for the release.
This includes an option to search in all address books at once, remove the 4GB mailbox is too large warning and the return of total message count and folder size in the folder pane.
Side Tip: disabling the blocklist pings in Thunderbird
If you don't want Thunderbird to ping Mozilla once per day for blocklist updates, for instance because you don't use plugins, add-ons and third-party software in Thunderbird, then you can do so in the following way:
- Open the email client on your system.
- Select Tools > Options from the menu at the top. If the menu is not there, tap on Alt to display it.
- Switch to Advanced > General in the options window.
- Click on Config Editor on the page that opens.
- Search for extensions.blocklist.enabled
- Double-click the preference to change its value to false.
You reset the preference at any time by performing the same operation again.
Now You: Which email client, app or service are you using?
Thunderbird is brilliant! I run a dual-boot Windows Linux desktop and the email profile is common to both. It doesn’t matter which OS I boot up, the emails are there and the folders are up to date. I can even get halfway through writing an email whilst using Linux, reboot into Windows, finish up the email and send it from there – seamless! What other Email client can do this? Long live the ‘bird!
And with this lovely comment, you’ve provided relief to an idea I was planning to implement over the next few days as I reinstall Thunderbird and attempt to have all of my mail located on my newly configured server, while accessing it from clients installed around my home.
Although I haven’t jumped into the full virtualization pool (still a little bitter by the implications/inevitabilities of virtualization to my IT kin), I am going for minimalist, quick nodes that all speak back to a semi-hefty server; the more I can put onto the server, the better.
My goal: Quiet PCs all around with minimal heat and loading times. …don’t wanna go too far down that train (because I’m far too excited to contain myself to three paragraphs lol) but, by your experience dual-booting, it should bode well for my Thunderbird aspirations.
Since I haven’t done this before, and am a couple days out, anyone have any ideas or pointers from their own experience running Thunderbird in this way?
(So happy to still be subscribed to this thread…)
@Tim. Good point . I never thought of that aspect.
Regarding “Side Tip: disabling the blocklist pings in Thunderbird”.
This is bad advice. Blocklist is more than just plugins. It’s also unreliable video drivers, etc.
I have just blown about 2hours or more … this ghacks.net is quite a find.
I was using Windows Live Mail … too slow.
Now PostBox a fork of Thunderbird … new version #4 is too much for this reptilian brain
– commercial but no forum and support is $10 per issue (non refundable)
Lately when my regular Windows PC was corrupted by a well known AV … I had to learn Linux real fast (on a very slow Acer)
– my first experience of TBird in about 12 years or more
On a 15.6″ laptop the TBird layout … “stacked” mail-list over view-email window is like watching TV through a keyhole.
– double-clicking the mail item to another window is hardly convenient when visually skimming for key-words
– Postbox has side-by-side UI … but their support is $10 per issue (non refundable)
Latest possibility to be trialed is Opera … the UI is customizable
– and if that doesn’t work it will be Thunderbird again
I have a 15.6″ laptop with high res screen. It’s perfectly usable if you install https://addons.mozilla.org/en-us/thunderbird/addon/theme-font-size-changer/
Answering “Chris” (2015-March 1) and perhaps others:
On Windows, I recommend you try the commercial program EverDesk (standard or Google edition). Each email is stored as an individual file inside either customary folders, or inside folders of your choice in your general file system, all visible and manipulable by the native Windows OS. This is a different concept from most email clients which store the emails within large databases which are properly readable only by the client software, and which can get corrupted, and which may or may not be easily exportable/importable to/from some other email client you might like to switch to; often the database formats are proprietary or have conversion limitations/difficulties. That should present less of a problem if your native OS can read and manipulate those emails. If you don’t like using conventional “Inbox/Sent/Outbox/Junk/Trash” and such folders, you can additionally or alternatively keep incoming emails within, and send new ones from, specific folders in your native file system pertaining to each of your projects, or categories, etc. … EverDesk will handle it that way, too. Text and HTML mail all work, in/out. However, interface lacks some features of Tbird, Outlook, etc.
I’m now also looking at Claws-mail (FOSS) which is cross-platform and small-footprint, easy on CPU. Like EverDesk, it stores each email as an individual file readable/manipulable by the native OS, here better used on the BSDs and Linux, although a Windows port has been done with a reduced feature set. Claws also incorporates PGP/GPG with plugins, but I read that the TAILS project discovered that it can leak your (intended encrypted) outgoing emails as plaintext using IMAP, but doesn’t have that problem when using POP/SMTP. Lots of features. Claws’ philosophy is to preferentially do all emailing as text-only (whether encrypted or not), aside from attachments, but the ‘nix versions have plugins to handle incoming HTML mail.
I’m a long-time Thunderbird user. I was attracted to its use of standards for mailbox files and displaying HTML email. But the thing it’s missing is access to email from everywhere.
I’m watching the development of MailPile (www.mailpile.is). With MailPile, all my email will still be encrypted at home, like Thunderbird; but I will be able to access the email securely from any device with an Internet browser.
The Bat! from Ritlabs (closed source) because I was using Windows. KMail because I was using KDE, now Thunderbird because it fits my needs.
I’m a little bit concerned that the 64-bit Thunderbird doesn’t have an official release.
Does anyone use text email like pine?
Someone mention Thunderbird SPAM/Junk and turning it off. It uses Bayes spam filtering and as you right-click and mark email it learns. To find out more go to the Preference -> Security tab.
T-bird at home for my ISP email account that is used primarily for private communications with close friends and family. Outlook at work and a variety of web-based email systems for the bulk of my personal mail.
I wish there was such a thing as a web-based T-bird that would pull in my email from all sources. Although web services like Yahoo and Hotmail/Outlook.com have improved quite a bit over the years, they still don’t provide all the capabilities that I get in T-bird.
We customized a build for our internal corporate use at work, about 3,000 users which fluctuates every so often as users move from exempt to non-exempt and go between our open source environment and Exchange.
I think this article is recommended reading:
https://medium.com/@trog/forgetting-firefox-c04dba853263
It talks about how Mozilla should devote resources to Thunderbird since Firefox is already a mature browser that has accomplished what it set out to do.
Martin, extensions.blocklist.enabled is present in Firefox as well
You are right. I think it makes more sense to keep it enabled in Firefox though.
Well, John Haller rocks. The work that he does is priceless, I’m a supporter, trust me. But, I’d rather download and use a program directly if I can and get only what I really need without a additional things that are needed to make/run portable apps. Plus, sometimes there are restriction when using portable apps or, you need to do additional things to do things like say, run multiple instances and profiles and the updates are more timely.
You can usually grab the programs from the Output or the software’s folder in PortableApps and use them, but, when I have the option, using just the program as it is, is the best for me personally. Maybe not for others.
Oh and I don’t need anyone’s approval to do it. :)
Well, John doesn’t exactly need Mozilla’s approval to do it, but he needs Mozilla’s approval to do it *and* call it “Mozilla Firefox, Portable Edition”. Otherwise, he might have to call it, Idunno, Pale Moon or some other such fanciful name. Yes, the–absolutely–#1 reason why I use Firefox Portable is how easy it makes it to run as many instances of Firefox (at any release levels) simultaneously as I want to. I seldom have only one running, almost always have several running, and often have half-a-dozen running at the same time. As for updates, you can update the same way as most other Firefox users do–with the internal updater–if you’re in that much of a hurry; or even, yes, your manual approach. Frankly, though, I’m never in all that much of a hurry to update to the latest release. Mozilla may want to do things “rapidly”, but I do not. So, I’m running the latest release off in the background somewhere while I’m still using releases one, two, or more versions back for real work.
I’ve used TB for years – just can’t get used to the webmail approach. I use the portable edition – not on a pendrive or anything but on a separate partition from Windows. Backup is a simple matter of daily copying onto an external HD (30 seconds), and restoring the same way if necessary. It’s a habit that’s saved my data time and again – haven’t lost an important email in over a decade (touch wood) despite changes of computer, new Windows versions, failed HDs, etc. In fact I’m continually surprised I have to go to people like PortableApps when Thunderbird is – IMHO – far more useful in portable format than installed.
I do a lot of emailing, even in these social-media (ugh!) days, and have a dozen email addresses (for perfectly proper reasons.) I just shudder to think of life without TB.
Only thing still missing for me is an Android app.
You actually don’t have to use the PortableApps version.
You can easily extract the files from say, Thunderbird Setup 31.5.0.exe and run Thunderbird without installing it as you would if it were a portable app.
You just need an extraction program.
I use 7-Zip.
Right click on Thunderbird Setup 31.5.0.exe icon > 7-Zip > Open archive > drag the “core” folder to the desktop, open it > thunderbird.exe
You can do the same with Firefox and a lot of other programs.
http://ftp.mozilla.org/pub/mozilla.org/thunderbird/releases/31.5.0/
and
http://ftp.mozilla.org/pub/mozilla.org/thunderbird/releases/
@ Ken Saunders
> You actually don’t have to use the PortableApps version <
Wouldn't this still write to the registry ?
They do say you learn something every day – I certainly do in this forum. I didn’t think I had much to learn about TB, but I certainly didn’t know that. Thanks Ken.
No, you don’t *have to*, but what you describe is only the first step of what John Haller does to create the PAF for Firefox and Thunderbird, all with the blessings and approval of Mozilla. Likewise with a lot of other programs.
Been using Tbird for years, I will never switch.
“Which email client, app or service are you using?”
Thunderbird since 1.0.
I love it and I like the bells and whistles.
Especially the privacy and security ones.
In the case of Thunderbird, the extra bells and whistles are called add-ons. :)
Here’s a collection that I created, although, I do need to spend some time checking them again with current versions of Thunderbird. I use around 30-35 of the ones listed and just discovered that one isn’t working (Extension List Dumper).
https://addons.mozilla.org/thunderbird/collections/-Ken-Saunders-/thunderbird/
I’ve also created a few add-ons myself specifically for Thunderbird, or that works in both Firefox, Thunderbird, and SeaMonkey. Some are for individuals like myself who’s visual acuity is less than perfect, or for those who use high resolution settings and big monitors.
The last I’m only a co-contributor.
Zoom Button for Thunderbird
(will be improving it soon)
https://addons.mozilla.org/thunderbird/addon/zoom-button-for-thunderbird/
Stylish Tools
Thunderbird, Firefox, SeaMonkey
https://addons.mozilla.org/thunderbird/addon/stylish-tools/
Theme Font & Size Changer (Featured Add-on)
Thunderbird, Firefox, SeaMonkey
(will be killing off the 1st run page after updates)
https://addons.mozilla.org/firefox/addon/theme-font-size-changer/
Forgot that I wanted to add a tip.
If Thunderbird starts up slowly, or even freezes, go to >
Tools > Account Settings > Server Settings (for each email account) >
uncheck “Check for new messages at startup”
It made a huge difference for me.
I’ve been a TB user since version 0.4 or 0.5. It’s always worked for me and I’ve not had any really major issue with it.
I just use it as an email client. When they introduced chat, I just took the icon off the toolbar. Although I tried it for a while, I learned that I do not need or want the Lightning extension. I use it for 9 email accounts, both POP and IMAP – but my main most important one is a POP account. I have 196 folders and subfolders. My only issue with it is that I don’t like the way it does searches – it will find what I’m looking for, but not tell me what folder it’s in.
I think the biggest problem others have with it is because most people keep all their messages in the Inbox – never moving them to folders, deleting messages and never compacting. See http://kb.mozillazine.org/Keep_it_working_-_Thunderbird
That is an improvement (more detailed search results) they should be able to make in the future with the rejuvenated development. Would be great!
OperaMail!
Not only would I like to see Mozilla focusing more attention on updating T’Bird, I’d like to see something in the way of an Android client with syncing. Keep dreaming, right? :)
That would be superb, for sure (an Android client).
For now, Blue Mail is working great for me in that arena. Give it a try if you haven’t. It’s “like” Thunderbird for Android for me…
Yep, already have…I agree, it’s the best out there.
I manage a mail server (post.office running on NT4) for a small company at $dayjob. I use Netscape Communicator 4.79 to pull various roll-account mail from it using pop (the server does not do imap). I love Communicator. I can scan various email archives for any sort of pattern – Return Path has this, User-agent has that, Received has this IP, etc. I do that a lot in order to see if the next /16 IP net-block I’m about to add to the server’s blocking list has ever sent “good” mail (I’m blocking somewhere around 70% of IPv4 space from being able to communicate with the server, and our spam load from zombies and “rent-a-server” hosts is maybe 3 a week these days). For normal work mail I (and about a dozen other people) are still using Office 2000 – which contains Outlook 2000 – which is still a perfectly workable mail client (I also use it on my home desktop machine). I do hate the fact that Outlook 2k doesn’t/can’t render jpeg’s inline (always displays them as attachments).
On my SO’s win-7 netbook, I installed Tbird about 4 years ago. It will move the odd incoming mail to a spam folder – and I have no clue what rules it’s using to do that or how to just turn off that “feature”.
I used Outlook when I was still working for a large corporation, and then got it for home use with Office 2003,
When no more free updates were available from Microsoft, I switched to WINDOWS LIVE MAIL, and have been using it since 2005 or so. Latest version is Live Mail 2012. It does most everything I need.It will do IMAP or pop3. I use both.
I agree with some of the other people that mail programs don’t need a whole lot of updates, but they do have to be updated so they continue to work well in a changing operating system environment. Security updates – yes we need those. Changing 4GB file restrictions, yes.
I used Outlook 2003 till it went unsupported after which I switched to Thunderbird (into which is was early to import all my emails and existing folder structure saved in my Outlook Date File). I use it daily to manage 4 email accounts and update to the latest version as and when it becomes available. While I now have Office365 so could use Outlook 2013 I am choosing not too since Thunderbird meets my needs. I regard the Lightening add-on as essential and wouldn’t be without and also like that I can use MozBackup to backup my Thunderbird account, making set-up after say a re-install of Windows a breeze (I also do the same with Firefox)).
@Peter I am interested to know if you are just accessing O365 mailbox via
POP or IMAP ie not EAS. You mention Lightning – how can you access O365 calendar with TB/Lightning ?
I cant access Outlook 2013 calendar via Thunderbird that why I use Lightening! I have only had a play around with Outlook 2013 just adding 1 email account to see what it like to use (a windows live email) but see no reason to move over to it not least because there is not straightforward to transfer my Thunderbird emails and folder set-up to it and anyway I just prefer Thunderbird’s user interface.
I read this article when it first posted…came back to see how many fellow Thunderbird users there are… Apparently I’m in relatively good, if not hyper-conservative, company. :-)
I use Thunderbird for managing five email accounts. There is truly no other way to do this conveniently without an email client. My first email client was Windows Live Mail…which worked fine, until I used Outlook (at work). From there, I knew I had to find another email client for home…and lo and behold, in comes Thunderbird.
Something I didn’t like about Windows Live Mail (and Outlook) was the fact that IMAP was not handled correctly; it seemed as if my other email accounts were not being polled unless I clicked on them. Thunderbird is the only email client that has done this properly for me, so I’ve stuck with it since.
Tried Opera Mail. Although the interface is straight to the point, and Opera Mail was the only client where messages from Electronic Arts showed properly (weird, I know), Thunderbird just has everything I am looking for… The calendar integration is superb with Google Calendar (via Lightning and Provider for Google), and the contact management via GContactSync work wonderfully and keeps me and my essentials nicely synced and up-to-date.
For you “Conservatives” who are still using the old versions, I may have to give v3 a spin on one of my other machines…seems interesting.
Given this rejuvenated Thunderbird development, perhaps Mozilla will work on lightening the load a little (500MB is kind of extreme…not that I’m short on RAM) and cleaning out the add-on library (no easy task I’m sure).
> perhaps Mozilla will work on lightening the load a little (500MB is kind of extreme…not that I’m short on RAM) and cleaning out the add-on library (no easy task I’m sure)
G Systems,
500MB could indeed be out of range for normal due to Lightning (a typical memory cruncher, which Thunderbird has no control over), or other addons. But if you find it’s NOT related to addons, please file a bug https://bugzilla.mozilla.org/enter_bug.cgi?product=Thunderbird or a support request https://support.mozilla.org/products/thunderbird
Thanks, Wayne. Indeed, memory leakage is why I got rid of Google Chrome…although in this case it wasn’t memory usage as much as installation size inflation (grew to almost 1GB install size). I guess this is my own personal gremlin, as others don’t seem to have the specific issues I have…which I guess I’m fine with as a SysAdmin…keeps me on my toes.
On Thunderbird, I am using Lightning, Provider, GlassMyBird, and a couple other extensions that likely ask a bit more of my memory. Again, I’m not too concerned as I have the maximum allowable memory for Windows 7 Home Premium, so I’m sure Windows is being a bit liberal with its addressing…
I use Thunderbird every day… version 3.1.11 — nothing essential has been added to Tb since. Security isn’t really a problem since I use only plain text and my email providers scan all messages for malware (and spam). Besides mail I use Tb (at a more current release level) for some feed reading; I think it may be the best reader available now for feeds that provide the complete article (as opposed to just an abbreviated snippet).
I check out the new releases now and then to see what’s really new and useful. Sadly, newer releases are also ugly (and by “ugly” I mostly just mean they waste so much space in the toolbox); Australis styling doesn’t bother me, and I like that Tb did finally add tabs; but the overall implementation has just seemed so “kludgey” (like there are hundreds of people working on it but they’re not working all that cohesively together). Anyway, email hasn’t really changed in decades, so the older versions work fine. Tb makes for an excellent notification program for multiple email accounts; I use it for that more than for back and forth messaging (for which I more often use a browser interface).
I also use Postbox (latest version) as my default client. Since it’s a glorified clone of Tb, I thought it was worth mentioning.
How much updating does an email client need? What is the obsession with constant updates? I have an online account . . . or two. But my main email is a pop-3 account that downloads to Thunderbird. I am using an old version of Thunderbird because I don’t care about a kazillion add-ons and changes in the interface. The way it is, it is small, quick, and problem free, just what I want from any software.
You are right that desktop mail clients don’t need constant updating or feature inclusions. However, there are features that would make sense to integrate into the client that are not available yet such as support for PGP out of the box or better handling of large mail databases.
Feature wise probably not much. Security wise it needs a frequent update. TB uses the same engine as FF does to display mail contents. Even if javascript and other toys are disabled, security holes are found and fixed time to time in the HTML/CSS renderer. Therefore with keeping an old version your system has become increasingly insecure.
There’s (probably several) addons and themes available if you’d like to keep the older UI look’n’feel just as I do (using Classic TB2 theme).
@Chris, on my wife’s Thunderbird on Win7, she is able to drag and drop a message to move it to another email folder or to copy it to a file system folder where it appears as .eml file. And I can do the same on SeaMonkey on Win7 & Win8. However, I don’t know if that function is available on the Linux and Mac OS X versions of Thunderbird. And, BTW, my wife’s Thunderbird does not even have the ‘save as’ function; just the ‘move to’ and ‘copy to’. SeaMonkey has all 3.
Since Yahoo redesigned its email, it has become completely unusable, so no web-based email for me. I preview my email in Mailwasher, then delete about 2/3 of it from my ISP’s server. The rest I download to TB for responding or keeping. Still using TB 2.0. Works for me. I don’t need a lot of bells and whistles.
I use Mailwasher Pro to preview my web based accounts then download to Outlook.
You can access your Yahoo email (and many other services) through Thunderbird.
https://help.yahoo.com/kb/SLN3217.html?impressions=true
I use SeaMonkey (which is Thunderbird and Firefox integrated into a suite using a different user interface) and my wife uses Thunderbird. I have 25 email addresses I have to keep up with (some IMAP & some POP) and over 150 folders. Filter rules sort what needs to go in which folder. I used Outlook Express until Microsoft discontinued it, then switched to SeaMonkey. Using a web interface would be okay if I had just 1-2 email accounts, but a good email client is great for keeping up with a bunch of email addresses.
Using Postbox after years of using PMmail
although i’m not a very heavy user of email (to say the least), i still like my conputer to fetch the occasional spam mail automatically, without me having to log in to my webmail first.
i tried several different mail clients over the years, from thunderbird to the simplemail firefox addon, to windows live mail and opera mail, but none ever really worked to my full satisfaction. i’m back at thunderbird for the time being and have to say that it works at least as well as the other contenders right now, although many things could be a bit more straight forward and made more modern.
when using thunderbird i feel set back at least ten years from a design standpoint, but as long as it works it’s good by me. add to that that mozilla is the name i trust the most when it comes to browsers and mail clients and it’s somewhat unlikely i’ll switch to a different software anytime soon.
Since Eudora isn’t around any more, Thunderbird has to do the job. ;-P
Seriously though, it’s nice having a client and not a web interface. I don’t like Outlook so Thunderbird is the best option out there.
I need an email client that allows me to save individual messages in a folder of my choice. That way, when I’m working on an extended project, I can save email in the same folder with documents and spreadsheets and such. I want to do this via drag-n-drop as opposed to the awkward Thunderbird method of “save as” and then navigate to the folder of choice.
Have you used any current email client? Because that’s an extremely basic task that pretty much all desktop email clients support.
Or am I misunderstanding what you want?
In Outlook for instance, you can add folders to the file structure on the left-hand side to drag and drop emails to, or you can literally just drag and drop emails from the inbox (or any other folder) on to your desktop/documents folder/whatever.
As mentioned, in Thunderbird you can simply select a message or multiple ones (hold Ctrl and click on each message), then drag them to whatever folder you want or create.
This also may be helpful.
https://addons.mozilla.org/en-US/thunderbird/addon/archive-this/
There are indeed several addons that can help you “file” messages to folders. In addition the the previously mentioned Archive This…
https://addons.mozilla.org/en-us/thunderbird/addon/quickarchiver/
https://addons.mozilla.org/en-us/thunderbird/addon/quicker-filer/
https://addons.mozilla.org/en-us/thunderbird/addon/quickfolders-tabbed-folders/
and perhaps more
I’m using ThunderBird and Outlook 2013 both for different purposes. I have Exchange Active Sync accounts in Outlook while IMAP and POP accounts in Thunderbird.
One thing that I don’t understand in TB is it’s search messages (Ctrl + K) and filter messages (Ctrl + Shift + K). It would be great if someone explains the difference between the two.
You have tried them both, yes?
It should be fairly self explanatory.
The filter searches the current view and only displays items based on the search criteria you provided. There is a bar that will appear below to specify which parts of the message you want to filter on (subject, sender, body, recipients).
The main search tries to be a bit smarter, attempting to make your results more relevant like a web search engine would, sorting the (hopefully) most relevant items at the top. Obviously it gives further options for whittling down your search results on the left.
Using TB and its predecessors (Mozilla Suite, Netscape) for my mails since the late 90s.
The increase of usage is not suprising as popular web based mail services has become increasingly unuseful in the last few years and since most of them provide IMAP access, TB is still a great UI alternative of webmail services used on desktops.
Works OK for me, I don’t need bells and whistles added for the sake of adding them so TB being ‘on the backburner’ isn’t a problem for me. Lightning *might* be useful though. Thanks for the news.
Using web based (various) also Microsoft outlook at work.
Tried Thunderbird more than once but found it a bit heavy and I also felt that when Mozilla put it “on hold” it might have been the beginning of the end – default to include Lightning sounds a good idea, might give it another go.
Carddav and Exchange support would be welcomed.
The SOGo connector Thunderbird extension is your *DAV friend: http://www.sogo.nu/downloads/frontends.html
It’s also now packaged for Debian and its derivatives (xul-ext-sogo-connectorpackage).
The SOGo Connector makes Icedove a full DAV client for any groupware server like SOGo, OpenGroupware, Citadel or Owncloud. The SOGo connector works through CardDAV so any application that provides CardDAV functionality will work with the connector.
The connector provides
* Event organizers
* CardDAV implementation for the address book
* Support for WebDAV access control lists (ACL)
* Free / Busy URL field in the address book
* Free / Busy functionality through HTTP
* Synchronization of the address book using GroupDAV