Thunderbird adds native Microsoft Exchange email support | Hacker News Reader

Thunderbird adds native Microsoft Exchange email support

blog.thunderbird.net

463 pointsbabolivier141 comments

While its been a long time since Ive used Thunderbird, I just wanted to take the time to publicly say thank you.

Many HNers probably wont (or cant) remember the world of desktop mail clients but basically during the height of MSFT dominance there was only one real mail client: Outlook. Which Microsoft was starting to monetize heavily, ignore UX, and keep it windows only (cant blame them for that).

Then Thunderbird arrived on the scene, an OSS mail client that beat the pants off of Outlook in features, spam detection, IMAP support and a bunch of other things.

And it was free.

And you could use it on any machine.

This was a huge moment for OSS.

We owe a lot of credit to Mozilla and Thunderbird for rescuing us from a closed source world.

Before Thunderbird, Eudora was fantastic. We ran it at a college I worked at for most of the staff and faculty, and it was a very sad day when Qualcomm shut it down.

Eudora was nice, but it wasn't available for Linux/BSD, and it wasn't open source.

Eudora was open-sourced in 2018.

see https://computerhistory.org/blog/the-eudora-email-client-sou...

and from https://en.wikipedia.org/wiki/Eudora_(email_client)

  The last 'mainline' (pre-OSE) versions of Eudora for Mac and Windows were open-sourced and preserved as an artefact by the Computer History Museum[2] in 2018; as part of the preservation, the CHM assumed ownership of the Eudora trademark.

  The only actively maintained fork of the software, known as Eudoramail as of June 2024, originates from 'mainline' Eudora for Windows as preserved by the CHM. Hermes, its current maintainers, describe Eudoramail 8.0 as currently being in alpha; Wellington publisher Jack Yan, meanwhile, points out its stability, a number of well-characterised and reproducible display bugs notwithstanding.

from https://en.wikipedia.org/wiki/Eudora_(email_client)#Hiatus_a...

  On May 22, 2018, after five years of discussion with Qualcomm, the Computer History Museum acquired full ownership of the source code, the Eudora trademarks, copyrights, and domain names. The transfer agreement from Qualcomm also allowed the Computer History Museum to publish the source code under the BSD open source license. The Eudora source code distributed by the Computer History Museum is the same except for the addition of the new license, code sanitization of profanity within its comments, and the removal of third-party software whose distribution rights had long expired.

recent news, see https://en.wikipedia.org/wiki/Eudora_(email_client)#Under_He...

Eventually, and I was glad to see it!, but way too late for it to matter much. I would've used Eudora when it was originally offered. Since I couldn't, I got comfortable with Thunderbird. And when my friends who used Eudora had to migrate off of it, I set them up with Thunderbird, too.

The time period under discussion ("before Thunderbird", and the heyday of Outlook lock-in, and I would also add before gmail) is well before 2018.

I used mutt at the time too, but I don't think it's in the same category as the graphical clients. For a while Gnome's evolution was also big in free OS circles.

Eudora was practically a CULT. I worked for one of their users who straight refused to use anything else, and one of my ongoing jobs as an admin was trying to get Exchange to play nice with it. It was maddening.

I fired it up several times for testing purposes, I don't get the hype, but man, for some people it was just the best damn software ever made.

It did its thing—internet email—really well. It was aimed squarely at the user with like a POP account, and it had a clean UI and plenty of features. For the time and use case, it was a fantastic client.

Outhouse tried to be too many things at once. Email client with HTML/rich text features that made it leave Microsoft crufties including mso: tags and the infamous J smiley all over your emails, contact manager, calendar. It was heavyweight, slow, and not quite there in terms of UI. But if you're an MBA type and you're committed to MSFT, or you're looking for a turnkey solution and it's this or Lotus Notes, Outhouse and Exchange sound like a win.

I've seen "The Bat!" pop up frequently in computer magazine CDs as well, not sure how widely it was used though.

The Bat! was absolutely the best email client. ever. way ahead of eudora. it was a massive step back when i switched to my first macbook in 2006 (the black one!) and started to use Thunderbird. That said Thunderbird is fantastic now and great to see it get native Exchange support!

What is it like to use The Bat?

It hits hard.

I used Pegasus Mail back when I was on windows. I then used elm and later pine for many years until moving to webmail entirely.

Pegasus is still around, and still receiving updates.

https://www.pmail.com/v49x.htm

Pegasus - wow, that brings back memories! Used it a lot.. and so also Eudora

Eudora had its own very distinct take on mail client UI. Many loved it. I never really got on with it, although I could use it.

While the native codebase is probably too old to salvage now, there was a project to write a Eudora-style UI for Thunderbird as an add-on. That might be easier to revive for 21st century email.

http://www.staroceans.org/wiki/A/Eudora_OSE

https://www.majorgeeks.com/files/details/eudora_ose.html

I know people that used it because it was self contained for Windows if I remember correctly. I remember one person running the installation off of a Zip drive back in the 90's. I warned them that Zip disks like to randomly self destruct and he'd better be making backups.

If you want that, there is Thunderbird Portable.

https://portableapps.com/apps/internet/thunderbird_portable

:-)

Thunderbird Portable + Dropbox FTW

Used to rely heavily on this, until an upgrade on one of my systems blew up the entire profile and I just stuck with webmail mostly. On my phone I have gmail, Outlook and Thunderbird (forked from K-9).

>cant blame them for that

Of course you can blame them for that.

100% this. It is an error of thinking not to blame them.

Personally I do not use thunderbird, but one elderly relative requires thunderbird. So I am all in favour of thunderbird getting better. Not everyone is able to use emails in a much simpler way. I actually, back when I was using gmail still, had some +4000 unread messages. I simply can not keep up with regular mail.

I still use Thunderbird and I love it. Even though I absolutely hate email and it is a chaotic clusterfuck we act like is bulletproof.

I'm incredibly impressed at how feature deficit email is, but Thunderbird gives a lot of power back. It's just a lot of little things that add up. Like why is tagging and sorting so hard? But Thunderbird makes it easy, giving you as many as you want and let you label as you please. In Gmail, Outlook, or Apple Mail you can't implement filtering, but in Thunderbird you can. There's just so many junk emails being sent from accounts I can't outright block and my inbox is a nightmare of chaos without these. Sure, I wish I could do regex and it was more feature rich, but it is strong enough that I can already catch a lot of emails that Gmail's spam detection misses. Like what the fuck is with this spam detection, it is missing things where my email is not even in the To or {B,}CC fields![0]

  > And you could use it on any machine.

The only thing I'm missing is on iOS. Email on my phone is a literal joke. Apple Mail[0.1] is the only one (compared to Gmail, Outlook, and Thunderbird) that previews a PDF. It seems like they're just helping scammers. I routinely get PayPal crypto scams and they look reasonably legitimate on Apple Mail but nowhere else. I could see how someone could be fooled, but I don't even have a PayPal account lol.

But on this note, we really do need to do something about email. We treat it so poorly. I use a lot of relay and proxy addresses now[1]. I'm also sending out a lot of resumes lately and it is surprising how we treat email. Like Microsoft only gives you SSO and then forces your email through that, not allowing you to add another email address. Not everything is "godelski@gmail.com", I use "linkedin@godelski.mozmail.com"[2] and "resume@godelski.com" (ditto [2]). In a world where we keep IDs for decades, where emails are constantly scraped and leaked, and where logins are tied to emails, these proxies are more important than ever. When I dump my gmail address I can also just redirect my two entry points (the mozmail and website domains) towards my new one. It is still not a great solution but at least it is easier to dump linkedin@godelski.com and move to new_linkedin@godelski.com than it is to go from godelski@gmail.com to godelski123@gmail.com.

If anyone has a better solution to this too, please let me know. I really fucking hate email and it seems like there's a ton of low hanging fruit

[0] The source of the email is a bit complicated and is clearly a LLM bypass by looking like generic emails like password resets or login alerts, but if my email was godelski@gmail.com it looks like it is sent to `godelski@gmail.com <bnchrch123@utahit.net>` CC `bnchrch1a2b@somehash.namprd04.prod.outlook.com`. It feels like we've gone backwards in spam detection. These are trivial to detect!

[0.1] And dear god, the least Apple Intelligence could do is run a god damn Naive Bayes filter on my text messages. You can surely do that on device! No Angela, I don't want to learn more about how I can make $500/wk and at no point in time have I ever wanted to accept a text message from a +63 country code... nor do I ever accept a call from my original area code as I haven't lived in the area for decades and it is a great filter to know who's spam.

[1] I use both Firefox relay and my personal website as Cloudflare gives you free email forwarding. Firefox relay integrates into Bitwarden (most of the time...) and it makes it really convenient for giving websites unique emails and unique passwords. Also helpful when you are given a piece of paper as you can create an email on the spot, block them as needed, and track how they're traded.

[2] I don't actually have the "godelski.mozmail.com" domain, so don't send me mail there. Though I wish relay would allow you to buy a second domain (and Signal would allow you at least 2 usernames!) At least give me one "clear" and one "handle".

> I'm incredibly impressed at how feature deficit email is . . . It's just a lot of little things that add up. Like why is tagging and sorting so hard?

If you read the specifications for the various email protocols, you'll soon discover that email, at the protocol level, is at its most feature-rich akin to flat files stored in a hierarchy of folders.

Tags, sorting, etc. are all the responsibility of clients. (Which is as it should be, since sorting is part of viewing data, not storing or sending it. Regarding tags, I suppose you could roll out a new email protocol, but SMTP is nothing more than a few text commands to send and receive bytes, and any tagging would be done by the client alone or the server alone as a value-add. The feature itself could not be implemented via, for example, the SMTP spec.

When you send an email via SMTP, you send the server "MAIL FROM" plus sender's address, RCPT TO plus destination, DATA and the contents of the email, and then a dot to represent the end of the email.

The email is then immutable. The receiver would be the one who wants to tag an email, and since the email is immutable, there's nothing you can do. And even if the sender wants to tag it, there's no command. I suppose in theory you could just add the tags to the email body, but every recipient not using your "improved" email format would just see that in the body of the email

Fair, but I think you missed the forest for the trees. You're right that I could be more clear but you also seem to understand that in context I'm discussing clients.

Nothing I've discussed has to do with protocol and everything has to do with clients, which is also in the context of what Thunderbird is. So I'm not sure why you're bringing up protocols as no one was discussing it until you brought it up.

In this context, the relevant protocol is IMAP, not SMTP. And IMAP very much has tagging and filtering, which is what Thunderbird exposes here. Heck, IMAP even has notes, you can attach to mails, so you could discuss mail drafts using plain IMAP, but no client I know exposes this.

> I'm incredibly impressed at how feature deficit email is . . .

It's getting better soon. Have a look at the jmap standard and stalwart, a high performant jmap server implementation in rust. This is the future!

I mean JMAP is an improvement, but I wouldn't say it's a drastic improvement. For Mobile clients, maybe. For everything else, I'm not so sure.

> The only thing I'm missing is on iOS. Email on my phone is a literal joke.

I hear you on that. I'd even go a step further and say Apple Mail on desktop is a joke too.

That led me to build Marco, an IMAP‑primitive, offline‑first, cross‑platform email client for web, iOS, and macOS:

https://marcoapp.io

> the world of desktop mail clients

We live in that world still.

> but basically during the height of MSFT dominance there was only one real mail client: Outlook.

On Windows, you had:

* Netscape Suite (later Seamonkey)

* Eudora

* Pegasus

and (edit:) two of those still exist. Plus, Outlook cost money (unless you used Outlook Express), while Netscape was gratis, and on Linux and most Unix variants, Outlook has never even existed. On Linux specifically there's Evolution and there's KMail.

And I'm sure I'm forgeting a few others.

> Then Thunderbird arrived on the scene

It was a development of the MailNews component of Netscape, to use the same XUL-based platform as Firefox. So, an evolution, not a revolution.

(edit:) Oh, look what I found!

https://missive.github.io/email-apps-timeline/

uncheck 'Web', iOS and Android.

I loved Pegasus. Specifically because to move it to another machine you just had to copy the PMAIL folder and make a shortcut. No registry awareness, no dependencies.

Thunderbird and Firefox are almost as easy. Just install the app on the new system and copy the data folder over.

Evolution was big too

Opera had an amazing built-in NNTP and email client. I think it was my first experience with views instead of folders, so my emails could appear in multiple "folders" (I think now we call them "smart folders").

Absolutely revelatory at the time.

Vivaldi has one now.

It is double weird because unix has always supported this.

I think was an accident of how the unix filesystem was implemented but basically, every file has at least one name but can have as many as you want, if a file ever has zero names it gets deleted. note that every open file is considered an additional name for that file.

By accident, I don't think it was designed this way but as they were putting together the filesystem "hey, what happens if two directories entries point to the same data?" anyone else "We will make a complicated locking system to prevent that from happening" the unix madlads "ship it and call it a feature, hell, work it into how files are opened as well then you can do tricksy stuff like open a file then delete it so it does not exists anywhere in the filesystem but it is still on disk"

The funny, in an ironic sense, thing is that while this this sort of naturally fell out of the first design of the unix filesystem it is not natural at all to modern copy-on-write filesystems, they have to do contortions to support it, but they do because it is now what people expect.

The thing you're describing is a "hard link" on the filesystem.

It can be done with directories too, but most modern systems expressly forbid that so you don't create a loop and put a directory inside itself.

I used, and even paid for, The Bat! at around this time, but as it was the emailer of choice for spammers, when spamming was a newish thing, I kept getting perfectly legitimate mail bounced and the developers had to constantly update the client to traverse the anti Bat internet! Which was a pain. I also used Opera email client for a while. Which was dross.

This is still the case, more or less.

Outlook has a lot of proprietary Office 365-only features that 3rd party clients will never support. Same with Google Workspace and the Google apps.

> Many HNers probably wont (or cant) remember the world of desktop mail clients...

If there are people who have never used a desktop mail client, I will say you owe it to yourself to try one. Web clients suck compared to desktop clients, it's not even close between the two. Sticking with just the Gmail interface (or whatever) is so limiting; definitely give alternatives a shot if you haven't.

> Sticking with just the Gmail interface (or whatever) is so limiting

Perhaps it's the fact that I grew up with Gmail throughout my education (and now my career), but most local clients lack one key feature - quick move!

My entire workflow around emails is based around opening & reading them, and then using the "Quick Move" button in Gmail to move it into a specific folder by typing the first few letters of the folder and hitting enter.

I know there are extensions for Thunderbird like Quick Folder Move [0], but I find these can be buggy, slow, etc. I presume these are just the realities of dealing with email providers who'd prefer you use their webmail clients rather than Thunderbird et al.

[0] https://services.addons.thunderbird.net/eN-US/thunderbird/ad...

Gnome evolution has shift-ctrl-v to move to a folder with typeahead search. I don't use the gmail webclient so I can't say how it compares.

I should note that I mostly use the emacs notmuch mail client, which requires having the mail mirrored locally (which I do with e.g. isync/mbsync), but gives really responsive and rich search and tagging capabilities

The biggest issue is if you're using IMAP with gmail itself, it's horrible and quirky.

I tried a couple of them, and they both started downloading my entire backlog of email to my hard drive, which I didn't want.

I couldn't think of a reason why this would be necessary, but I haven't really kept up with how the technology has evolved in recent years. Is this behavior intrinsic to desktop clients?

You can't think of a reason why you'd want a local copy of your mail? Do you have control over any of your data?

I can think of reasons why I might want a local copy, but they didn't apply in my case.

Do I have control over my data? I'm not sure I understand the question, but in this case the answer seems like a clear no, as my employer manages the email server.

There are options in Thunderbird to disable syncing completely or only sync messages from the last 30 days and such.

Definitely make sure to adjust your defaults if you decide to dip your toes into nntp... I hate some of the defaults there... namely the reply/respond button defaults. Usually you want to respond to the group, not send an email to the poster.

That said, NNTP is so dead at this point, outside some active BBSes that offer NNTP access. Usenet definitely feels like a wasteland when I've looked around the past couple years.

Intrinsic, no. Common, yes. Many people who use desktop clients want a local copy of a substantial fraction of their email so that they can review or compose messages while off-line. Desktop clients also operate faster and can provide robust search services only if they have a cached copy of the messages on disk.

I have tried thunderbird. Gmail is 10 times more usable and readable and performant than thunderbird.

Outlook was better than Lotus Notes at least.

MS Outlook was a heaven for viruses.

Lotus (even before Notes) had cloud-like features for mail and worked on Windows and OS/2.

It also had a password dialog that showed fun hieroglyphs as you typed, instead of dots or asterisks. But, oops, those would change deterministically depending on what you typed.

What, you don't think people were flocking over to Mutt?

When I was first getting into Linux, I liked Evolution a lot, though admittedly I haven't used it in awhile. Honestly I haven't really used Mutt in awhile either; webmail is just easier.

Evolution is great; it's also had outlook EWS (including Oauth2) support for several years now. I am still mystified as to why Thunderbird is so much more popular (though nice to see that thunderbird is getting some much needed TLC more recently).

Thunderbird is the only MOZ product that I still use daily - almost at par with Mail.app if not more, and I hope to keep using it unless they eventually release the iOS Thunderbird after making it unrecognisable to me and ensuring that some of the differentiating Thunderbird features are missing – like the ability to send email from any address on a domain by just editing the "From" field - of course, it will work only if you own that domain. But it's a feature I can't do without (and utilise it a lot on desktop). Then there are forever pending things like maildir support :)

> Then Thunderbird arrived on the scene

Apologies, but in my memory Thunderbird is just the new name for Netscape Mail. And Netscape mail, I believe, is older than Outlook.

I still have folders in my current Thunderbird that I created in Netscape (for example the 1996 folder that contains all mail from 1996).

Yeah, same with Firefox, to me it's just the new name for Netscape Navigator.

I still got some bookmarks carried over from Navigator... though I bet 95+% don't work anymore.

Thunderbird, via the Enigmail extension[1], also was many folks first foray into applied cryptography.

https://en.wikipedia.org/wiki/Enigmail

During "the height of Microsoft dominance" Eudora, Outlook Express and Pegasus Mail were seen much more frequently for users than Outlook.

As former Exchange admin/Office365, it's using EWS (Exchange Web Services) which is being removed in October 2026 for Office365. So for most, this is extremely time limited.

EDIT: EWS continues to be supported for on premises Exchange and is not scheduled for deprecation.

How do you know Thunderbird is using EWS, not MAPI? MAPI is not going away any time soon.

Read the docs? https://blog.thunderbird.net/2025/11/thunderbird-adds-native...

Yikes, thanks. Enjoy this feature while it lasts, I guess. EWS is getting nuked.

Read the article?

> it's using EWS (Exchange Web Services) which is being removed in October 2026 for Office36

This is Microsoft we're talking about here, so if its slated for removal in Oct '26, it will be put into LTS, and finally 'retired' (but operational) _starting_ around 2031.

Microsoft swears it's happening: https://techcommunity.microsoft.com/blog/exchange/retirement...

Take the blog article for what you will. I have noticed in Office365, they tend to be less backward compatible than you would expect from Microsoft.

  > Microsoft swears it's happening

And when has that ever meant it comes without delay?

Up to you if you believe Microsoft or not. I don't really care, I haven't messed with 365 outside being end user in years.

to be fair with you, EWS has been deprecated since I think 2014, so we're already in the "pushed" window.

As an on-prem admin, I am blown away that there's 30-40 changes to 365 monthly, often including at least two or three feature deprecations. It seems like building a building on top of quicksand.

The have been keeping to the timeline when it comes to other recent Exchange Online removals (certain auth roles).

The new Microsoft is unfortunately not like the old one.

As you imply though, it remains for on-premise. They're working on msgraph as well luckily.

I updated my post to reflect yes, this is Office365 only. On premise will continue to support EWS. Depending on where you are, Exchange on premise is becoming extinct.

The Thunderbird blog post also mentions they are looking to support the Microsoft Graph.

More limiting is that the current release doesn't support custom Office365 tenant IDs. So basically, unless you are using outlook.com this won't currently work yet. I'm lucky that my org hasn't disabled SMTP and IMAP, but it's been so slow lately...

Someone might be wondering why someone might have different URLs. One example is anyone under sovereign clouds (eg. GCC, GCC-High) which use different URLs (and TLDs) across the board (eg outlook.office365.us)

You'll recall how horrendous on prem Exchange updates could be. Surely the sheer amount of time involved was a nudge and nothing technical?

My tiny company had an on prem Exchange, migrated from GroupWise, and is now cloudy. I did all the migrations myself.

I have left things with our MX records pointing to on prem (Exim + rspamd + stuff) and relaying to MS 365 and a few IMAP daemons. If MS take the piss with licensing costs, I'll simply relay elsewhere and drop them.

Then I'll migrate my customers away. It'll take a while but it is not insurmountable.

FWIW: I use Evolution on my Kubuntu based gear to access M365 email. Wifey rocks Arch and I've deployed Evo on KDE there too.

What I'm most curious about, and what the docs are light on detail about: does this mean Thunderbird complies with remote deletion requests (which IIRC, the Exchange protocol suppports)? I have the impression that Microsoft makes this a requirement for Exchange implementations, which is why third-party devices and apps like Apple's Mail cooperate with those requests.

That would be Active Sync:

https://learn.microsoft.com/en-us/exchange/clients/exchange-...

Not sure how Mozilla went about the implementation, but I do agree it would be a concern to verify before using.

You can perform the following Exchange ActiveSync tasks:

    Enable and disable Exchange ActiveSync for users

    Set policies such as minimum password length, device locking, and maximum failed password attempts

    Initiate a remote wipe to clear all data from a lost or stolen mobile phone

    Run a variety of reports for viewing or exporting into a variety of formats

    Control which types of mobile devices can synchronize with your organization through device access rules

Some clients perform some of those operations in a sandbox. Eg. Nine for Android let's you choose when you set up an account whether a remote wipe command should just wipe that account's local mailbox, or your whole device.

ActiveSync will forever be reserved for the technology I used to sync email and calendar on my HP Jornada 430 running Windows CE - just like James Bond did!

Do you mean recall? https://support.microsoft.com/en-us/office/recall-an-outlook...

That only works within an organisation, right?

Otherwise you just get an email. I got one recently.

No, Exchange ActiveSync (as the other commenter correctly identified it) really allows an admin to wipe your device - ostensibly of mail, but often of all other data as well.[0]

If your Outlook server disables IMAP & POP3, then the ActiveSync protocol is AFAIK the only way to get in-app emails on your phone. Admins do this so that they can forcibly wipe the device if they "need" to.

0: https://learn.microsoft.com/en-us/exchange/clients/exchange-...

I was not sure which you meant.

Historical note: There was also MAPI for a long time (and I believe MAPI over HTTP/S)

Still is

This may turn out like those PDF "security" features, i.e. easy to patch out and ignore.

It actually downloads BleachBit and runs it so that even god can't read your emails /s

Nice to see, but unfortunately it's not uncommon for orgs using Outlook/Office to disable Exchange client support and require use of the official clients. It's highly unlikely and maybe not even possible, but I'd like to see desktop and mobile mail clients implement some kind of workaround.

Microsoft plays wack a mole with 3rd party clients trying to gain access when it's been disabled so it's thankless job for their developers. Not to mention, if I'm disabling your third party access, trying to circumvent is Employee policy violation and you get to talk to HR about why you don't want to play by the rules.

> Not to mention, if I'm disabling your third party access, trying to circumvent is Employee policy violation and you get to talk to HR about why you don't want to play by the rules.

If you want your employees to install malware, maybe you should issue them a company device instead of requiring them to install it on their personal device.

I was responsible for third party e-mail clients able to connect to Exchange, it was decided Thunderbird was allowed and support was implemented. It can be done if people are aware of the needs, can implement it securely and can evaluate risks.

I've been using Outlook Lite on my phone for a long time because I don't want to give my employer admin rights in my phone, and I'm getting messages that that is now deprecated. I guess I'll go back to webmail in Firefox Mobile.

So far this extension was a solution for accessing Mail-Accounts hosted on Exchange and even O365 by using OWA in a miraculous manner. It‘s not easy to overlook how this compares for simple end-user.

Owl for Thunderbird https://reviewers.addons.thunderbird.net/en-US/thunderbird/a...

Was and still is a solution. I use this functionality daily and it just works. Very satisfied to be able to use Thunderbird on my work Linux install.

All facts aside, Thunderbird is portable, you can install it on usb and carry your mailbox in pocket, connect to any pc and access without touching host filesystem, if pc has internet browse new mails and all

i always carry it on pendrive with encrypted partition, and encryption software is also natively installed on usb, so no use of host pc for anything, mail or decryption

Not just that, you have all your emails with you, even without internet, even when aws/azure/cloudflare/... fails, plus you can write replies and everything else while offline and just send/sync when you get internet access (eg. on a cheap flight with expensive wifi).

Many things don't need an app, a web site is enough (and they somehow force apps onto us), but email, especially with something like thunderbird is a great thing to have directly installed on your pc (or portable with you).

And you randomly use public or other peoples computers? Seems more inconvenient than just having email on your phone.

I generally like Thunderbird... but something is weird. What ever happened to Sync? It was around the corner for next release like two years ago. And I'm not complaining about Exchange support, but I am a bit sad that JMAP is nowhere to be found yet.

We implemented this in the Daily build of the desktop app last year, using a staging environment for Firefox Sync. But Firefox Sync is called Firefox Sync because it’s built for Firefox. Thunderbird profiles, in comparison, have a lot more data points. This meant we had to build something completely different. As we started to spin up Thunderbird Pro, we decided it made more sense to have a Thunderbird account that would manage everything, including Sync. Unfortunately, this meant a lot of delays. So Sync is still on our radar, and we hope to have it next year, barring further complications. Source: https://blog.thunderbird.net/2025/09/state-of-the-thunder-mo...

In other words, it was more work to adapt Firefox Sync than they thought at the beginning. It's still actively developed so finger crossed it's coming soon.

The lack of native Microsoft Outlook support was one of the reasons I've abandoned Thunderbird.

However, it is still not enough for me to come back. Sadly, corporate life is often organised around email and calendaring. All these endless meetings everyone complains about, which need to be scheduled, accepted, rejected, re-scheduled, etc. The native Exchange support does not yet support Calendar integration. Without it, it will be very awkward to use in a day-to-day corporate environment.

I barely ever open outlook at work. In fact I only open it on the webmail when someone asks me on teams if I have read their email.

Much quieter that way as you only get to hear about the important stuff and can ignore the rest of the noise.

Unproductive culture.

Awesome news, can't wait until they implement calendar support and I can get rid of Outlook once and for all.

Yeah, me too

great to see thunderbird joining evolution in supporting ews among free software email clients.

evolution has been keeping me sane whenever i needed to use ews for years.

Lacking calendar and contacts sync are a critically missing feature here. I'm not sure what there is to like here above IMAP access.

Aside: Mozilla should really create a nice full-featured email server with the features found in Exchange/O365 for use with Thunderbird... it's a space that desperately needs competition and more solutions.

Guess this means I can cancel all my OWL subscriptions.

I'll stick with Owl for a while longer. This native feature doesn't support calendars or address books, making it essentially worthless to me.

Also it's based on a protocol that's dying (slowly).

Good to see they're attending to exchange support, but this is a lackluster step.

I’d be more excited for thunderbird if it worked on an open source alternative to EXCHANGE SERVER. Firefox and thunderbird are clients. But it is time they launched servers as well. There might not be any advantage to another https server. But a new mail server with a new email client protocol would be exciting. And maybe a WebDAV server that Firefox could work with natively.

There are several open source mail server options available.

The only real new protocol is JMAP which is pretty good and I’d much rather more clients and servers support JMAP than create a new protocol altogether.

I can recommend trying out Mox as an email server. The author built everything from scratch and does a lot of great work when it comes to unifying everything. The wizard spits out all the discovery, DKIM, DMARC, DANE and MTA STS related subdomains you have to change the entries of (that is the most painful part) but everything else really works like a charm.

Much much easier installation process than weeks of trying to make postfix and dovecot work.

[1] https://xmox.nl

[2] https://www.xmox.nl/protocols/

Take a look at Open-Xchange, it's not developed by Thunderbird folks but otherwise fits the bill.

https://en.wikipedia.org/wiki/Open-Xchange

mailbox.org is based on it.

I like Thunderbird, it’s a great tool for private use. One killer feature I always missed (not sure if it exists today by default in Thunderbird), is the great calendar integration of outlook. I use the calendar a lot, during work but also to organize our family. It’s super important for me to able to send invites to co workers and my wife :-)

Since last year, TB has native caldav/carddav support.

I've never seen a piece of software that managed to implement all of the iCalendar specification, which to me seemed like a data model for a good productivity app that's just never manifested. iCalendar (RFC 2445 from 1998) outlined not only events but todo and a journal component for memorializing meetings. Outlook seems to ignore VTODO entries in iCalendar completely, and VJOURNAL support is deprecated.

Thanks!

I have a few Exchange inboxes and once MS forces the “New Outlook” design, without allowing the legacy option anymore, im gone!

Interesting, but I wonder if the Oauth with Yubikeys is fixed yet?

My work email is behind Okta and I can get through the whole flow of Oauth up till it hits the WebAuthN..which works but it won't display a pin entry dialog.

Sweet memories of several email clients mentioned here.

I also remember the mail client built into the old Norsk version of Opera. I loved that, a much as I loved that browser.

I take it mutt still does not have native Microsoft Exchange support?

Davmail is the shim I used to proxy OWA / exchange ansmd present an IMAP interface towards neomutt. Used this setup with three companies, worked well, and unified the UX instead of the different Gmail and Outlook web slowness.

Doesn't work for me, and the account creation window itself is buggy with poor UX, throws a general error and requires me to retype password each time I try to use a different set of settings.

Fantastic news! I've been hoping for Exchange support for a long while.

Hi guys, what email client would be most suitable for managing 100++ mailboxes with the unified inbox option? Is there a local or self hosted options that you could recommend? Yes that’s for outreach

Try Thunderbird

(OFFTOPIC!)

I would not recommend that with any email clients. Most are built with the assumption that you have around 3 to 8 accounts. UI, speed, and configuration may become an issue. Esp. the unified inbox in Thunderbird was slow in my personal use.

What are these mailboxes? Are they changing a lot? That's also a factor to decide in your setup.

If you have hundreds of mailboxes, and you're posting on HN here, chances are you are technically competent. I would recommend a local IMAP server like Dovecot or Stalwart installed as Docker, and then fetchmail or similar to pull (copy) all the mail into a single inbox. And then your email client uses only that one account which has all emails.

This is great news because the new version of Outlook is terrible. When the good old Win32 version goes away, everyone will be looking for an alternative.

Nice! I have been paying for ExQuilla because my university's IT department disabled IMAP and only supports Exchange...

Is this good?

This is a genuine question. I am not sure whether this is good or not.

It seems to only extend existing options? Or is there some trade-off?

This is awesome!

For one to have an open-source client to Exchange online and on-premise with broad support for more than plain email management. And also for other servers like Kerio Connect and grommunio.

Current limitations:

  Search & filtering
  Filter actions requiring full body content are not yet supported.
  
  Accounts hosted on Microsoft 365
  Domains requiring custom OAuth2 application and tenant IDs will be supported in the future.
  
  Accounts hosted on-premise
  Password-based NTLM authentication and OAuth2 for on-premise servers are on the roadmap.
  
  Calendar support
  Not yet implemented – calendar syncing is on the roadmap.
  
  Address book / contacts support
  Not yet implemented – address book support is on the roadmap.
  
  Microsoft Graph support
  Not yet implemented – Microsoft Graph integration will be added in the future.

To be honest, it's disappointing that this lacks calendar and address book integration (for now). There's plenty of prior art in terms of delivering full functionality via EWS, and I'm surprised their first release is this spartan. It's not like they're trying to support MAPI or something else that would need to be reverse-engineered.

My solution 15 years ago, when I needed to support Linux users, was Thunderbird plus a middleware tool called DavMail. Something like that is probably still the best option until Thunderbird is able to deliver more full functionality. Nice to see them working on the thing, at least.

Does it implement the famous "sweep" feature from Outlook?

This is wonderful. Thank you Thunderbird!

Microsoft could have effortlessly made it easier for others to implement integrations with Microsoft Exchange but they won't. They needed to make sure as many people as possible get vendor locked.

Imagine going to work, and having a meeting about how you can make it harder for your software to interoperate with other software. Or waking up in the morning and spending your day designing a proprietary protocol designed to prevent interoperability. That's just another day at Microsoft.

"OSS projects have been able to gain a foothold in many server applications because of the wide utility of highly commoditized, simple protocols. By extending these protocols and developing new protocols, we can deny OSS projects entry into the market."

It's funny because now the OSS starts supporting extended protocol. Guess MS's next step

What took so long?

WONDERFUL. If it works, literally life improving for me. My browser slows to a crawl with the silliness like copilot on the side.

And at the risk of asking too much (because this was a thing we used to have as a plugin)...

...any possibility of color-coding separate accounts?

I'm now aware of three protocols that Exchange has used: MAPI, EPW, and Microsoft Graph. Are all of these supported/commonly used in both on-premise and Office365 environments, are are some limited to one or the other?

Reply on news.ycombinator.com