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Thunderbird Adds Native Microsoft Exchange Email Support

and 16 responses

If your organization uses Microsoft Exchange-based email, you’ll be happy to hear that Thunderbird’s latest monthly Release version 145, now officially supports native access via the Exchange Web Services (EWS) protocol. With EWS now built directly into Thunderbird, a third-party add-on is no longer required for email functionality. Calendar and address book support for Exchange accounts remain on the roadmap, but email integration is here and ready to use!

What changes for Thunderbird users

Until now, Thunderbird users in Exchange hosted environments often relied on IMAP/POP protocols or third-party extensions. With full native Exchange support for email, Thunderbird now works more seamlessly in Exchange environments, including full folder listings, message synchronization, folder management both locally and on the server, attachment handling, and more. This simplifies life for users who depend on Exchange for email but prefer Thunderbird as their client.

How to get started

For many people switching from Outlook to Thunderbird, the most common setup involves Microsoft-hosted Exchange accounts such as Microsoft 365 or Office 365. Thunderbird now uses Microsoft’s standard sign-in process (OAuth2) and automatically detects your account settings, so you can start using your email right away without any extra setup.

If this applies to you, setup is straightforward:

  1. Create a new account in Thunderbird 145 or newer.
  2. In the new Account Hub, select Exchange (or Exchange Web Services in legacy setup).
  3. Let Thunderbird handle the rest!

Important note: If you see something different, or need more details or advice, please see our support page and wiki page. Also, some authentication configurations are not supported yet and you may need to wait for a further update that expands compatibility, please refer to the table below for more details. 

What functionality is supported now and what’s coming soon

As mentioned earlier, EWS support in version 145 currently enables email functionality only. Calendar and address book integration are in active development and will be added in future releases. The chart below provides an at-a-glance view of what’s supported today.

Feature areaSupported nowNot yet supported
Email – account setup & folder access✅ Creating accounts via auto-config with EWS, server-side folder manipulation –
Email – message operations✅ Viewing messages, sending, replying/forwarding, moving/copying/deleting–
Email – attachments✅ Attachments can be saved and displayed with detach/delete support.–
Search & filtering✅ Search subject and body, quick filtering❌ Filter actions requiring full body content are not yet supported.
Accounts hosted on Microsoft 365✅ Domains using the standard Microsoft OAuth2 endpoint❌ Domains requiring custom OAuth2 application and tenant IDs will be supported in the future.
Accounts hosted on-premise✅ Password-based Basic authentication❌ 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.

Exchange Web Services and Microsoft Graph

While many people and organizations still rely on Exchange Web Services (EWS), Microsoft has begun gradually phasing it out in favor of a newer, more modern interface called Microsoft Graph. Microsoft has stated that EWS will continue to be supported for the foreseeable future, but over time, Microsoft Graph will become the primary way to connect to Microsoft 365 services.

Because EWS remains widely used today, we wanted to ensure full support for it first to ensure compatibility for existing users. At the same time, we’re actively working to add support for Microsoft Graph, so Thunderbird will be ready as Microsoft transitions to its new standard.

Looking ahead

While Exchange email is available now, calendar and address book integration is on the way, bringing Thunderbird closer to being a complete solution for Exchange users. For many people, having reliable email access is the most important step, but if you depend on calendar and contact synchronization, we’re working hard to bring this to Thunderbird in the near future, making Thunderbird a strong alternative to Outlook.

Keep an eye on future releases for additional support and integrations, but in the meantime, enjoy a smoother Exchange email experience within your favorite email client!


If you want to know more about Exchange support in Thunderbird, please refer to the dedicated page on support.mozilla.org. Organization admins can also find out more on the Mozilla wiki page. To follow ongoing and future work in this area, please refer to the relevant meta-bug on Bugzilla.

Tags: Exchange

16 responses

Harrie wrote on

Exchange is Public but not safe and not finished! No NTLM-authenticatie en OAuth2! hackers love this, they just walk in to your network.

Monica Ayhens-Madon wrote on

Thanks for your concern! OAuth2 is supported for what is by far the largest provider, NTLM is in progress, and we’re working on OAuth2 support for additional providers.

熊澤 幸則 wrote on

If I had to nitpick, I wish the workplace environment had been set up before migrating to Microsoft 365. That way, we wouldn’t have had to migrate mailboxes either.
Exchange support is crucial in our current environment. That part itself is welcome.
I also wonder if they could support Mastodon. It would be great to consolidate messaging into Thunderbird.

—-— DeepLで翻訳しました (https://dee.pl/app)

欲を言えば、職場の環境がMicrosoft 365に移行する前に対応して欲しかった。そうすればメールボックスの移行もしなくて済んだ。
Exchangeのサポートは現在の環境ではとても重要だ。それ自体はうれしい。
あとはMastodonに対応してくれないだろうか。メッセージングをThunderbirdに集約できれば。

Monica Ayhens-Madon wrote on

Thank you for the feedback, and we hope this is still a good experience for you! And you can also upvote and comment on this suggestion to add Mastodon (and general Fediverse support) to Thunderbird: https://connect.mozilla.org/t5/ideas/mastodon-lemmy-and-pixelfed-support-in-thunderbird/idi-p/30354

Toengel wrote on

Hi,

do you know, that it is called “on-premises” – with S at the end? The word “on-premise” is just wrong… 😉

Toengel@Alex

Monica Ayhens-Madon wrote on

Thanks for the feedback! Looks like that’s a pretty common slip: https://www.datacenterknowledge.com/cloud/the-on-premise-debate-how-a-data-center-slang-term-went-mainstream

Cliff wrote on

As you’re adding MS EWS functionality so that presumably TB can be thought of as a true alternative to Outlook etc., you should also look to embed the standard “Outlook style” reply header as a native TB function (as an *option*, not forced). As soon as people trying TB, who are used to that header style and like to use it, see the minimal Unix style “On Date Name said…” they will straight away ask questions about whether TB is a real alternative. They are unlikely to know about or think to search for the ReplyWithHeader plug in. This has needed doing for ages and the semantic discussions about why this is not needed have become old and tired. It’s also easy – the code is there since it’s used for Forward-ing headers and there’s a 3rd party plug-in that does the lot (and more).

Monica Ayhens-Madon wrote on

Thanks for the feedback on the Outlook-style header as an option, and there’s a similar suggestion on Mozilla Connect (https://connect.mozilla.org/t5/ideas/custom-reply-headers-like-in-outlook-custom-date-format/idi-p/29379) that you can comment on and support in addition to the feedback here!

Dean wrote on

Great news about native Exchange support — thanks for the update!
One thing wasn’t fully clear from the blog post: it only describes setting up a new Exchange/EWS account, but doesn’t mention what happens with existing IMAP accounts.

I’m using Microsoft 365 Business Basic (Exchange Online), and currently have an IMAP account with about 50 GB of offline-synchronized mail in Thunderbird.
Is there any supported way to migrate this existing local IMAP data to an EWS account, or is the only option to add a new EWS account and later remove the IMAP one?

Monica Ayhens-Madon wrote on

Unfortunately there’s no means to migrate from IMAP to EWS, so you would need to add a new EWS account, as you said. But if your account admins continue to enable IMAP, there’s no urgent reason to switch.

Gregory Orange wrote on

This is excellent news, thank you! I have been using Exquilla and then Owl for some years, and that was a good stopgap, but native support is far better. I’d prefer to redirect my few bucks a year to the foundation than a business, even though I was quite willing to support them doing the good work to maintain it.

I will hold off on the change over until calendar support is released, but this certainly gives me hope.

Monica Ayhens-Madon wrote on

Thank you for using us! We’re grateful our users had an option for Exchange support and continue to have it while we add calendar. Calendar support will be the next priority after we have Graph support working for the October 2026 deadline and the Calendar UI work is done next summer!Stay tuned here at the blog for our updates in the Monthly Development Digest and any extra blogs.

Wolkenfarmer wrote on

Ahh, I really want all these new great features from the release channel, but I also do not want to leave the official Thunderbird Flatpak, which is currently only offered for the ESR channel.
Any updates on when we Flatpak-lovers can finally migrate to the new release cadence and enjoy all the new stuff?

Monica Ayhens-Madon wrote on

Right now, the plan is to move the Flatpak to the Release channel by default next summer around the time of the next ESR, which is usually at the end of June/beginning of July. We definitely want our Linux users to have an easy way to get all these new features every month!

Luca Andena wrote on

Just a question. I already use Thunderbird as my email client (can’t really tolerate Outlook with its cluttered interface). In fact, with my work email account set up with IMAP everything runs just fine.
Do I need to change anything? Or, better, would there be any improvement in changing my account from IMAP to EWS?

Monica Ayhens-Madon wrote on

If you’re running well with IMAP, there wouldn’t be much benefit to switching, and no, you don’t need to change anything! The only reason you might would be if your work administrator made any changes on their end.

Comments are closed.