Thunderbird adds native Microsoft Exchange email support

Posted by babolivier 11/19/2025

Thunderbird adds native Microsoft Exchange email support(blog.thunderbird.net)

463 points | 141 commentspage 3

vorprokuror 11/19/2025|

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

benbucksch 11/19/2025||

(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.

InMice 11/19/2025||

Try Thunderbird

nipperkinfeet 11/20/2025||

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.

spacechild1 11/19/2025||

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

shevy-java 11/19/2025||

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?

cachius 11/19/2025|

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.

tehdely 11/20/2025||

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.

Onavo 11/19/2025||

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

AndyMcConachie 11/19/2025||

This is wonderful. Thank you Thunderbird!

29athrowaway 11/20/2025||

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.

tralarpa 11/20/2025|

"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."

enbugger 11/21/2025||

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

RagnarD 11/20/2025||

What took so long?

jrm4 11/19/2025|

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?

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