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 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.
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.
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.
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.
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.
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.
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!
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 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.
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.
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").
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.
> 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.
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.
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
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.
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.
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.
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)
> 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.
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.
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.
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.
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!
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.
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.
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’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.
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.
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 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.
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 :-)
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.
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
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.
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.
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.
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