• Development

Thunderbird Monthly Release 144 Recap

We’re back with our Monthly Release recap! Thunderbird 144.0 readies the way for Exchange Web Services support, makes reordering your folders easier, and adds a new UI for TLS certificate handling. Additionally, we’ve fixed a dark mode toggle bug for High Contrast Mode users.

A quick reminder – these updates are for users on our monthly Thunderbird Release channel. For our users still on the ESR (Extended Standard Release) channel, these updates won’t land until next July 2026. For more information on the differences between the channels and how to make the switch:

• Visit the Release download portal: Thunderbird Release Page.
• Explore detailed comparisons and migration guides.

Now let’s dive into what’s new in 144.0!

New Features:

Support for Exchange Web Service (EWS) Email in Account Hub

As part of our preparation for EWS support officially landing next month in Thunderbird 145.0, you’ll notice EWS accounts as an option in the Account Hub. We will have more detailed blog posts and support articles available next month describing what is and isn’t supported. 

Benefits:

• This gives us a chance to gradually ready the app and users for our newest protocol

Improve UX of folder reordering

Bug 1957486

We recently introduced drag and drop folder reordering, and in 144, we’re making it better. A new widget shows where your folder is going. We also fixed an issue that prevented the visual from showing. We removed the jitters when positioning between folders, and Improved consistency by using the same indicator used to reorder tabs and attachments.

Benefits:

• More control over drag-and- performance with fewer folders going to the wrong location
• More visual consistency

New UI for TLS Certificate Handling

While power users might be comfortable handling TLS certificates, average Thunderbird users might not know what to do when Thunderbird doesn’t trust a server’s certificate. This UI makes these issues, when they occur, harder to ignore and easier to diagnose and fix, even for less tech-savvy users. 

The new UI will mark the server red, with a clickable icon that takes users to an updated server settings. There, users can view certificates and add or remove certificate override exceptions.

Benefits:

• Increased security for the average Thunderbird user
• Easier access, via the server settings, to certificate actions

Bug Fixes:

Dark mode won’t go away for messages in High Contrast Mode

Bug 1976900

Our High Contrast Mode users noticed the new toggle for messages in dark mode wasn’t appearing. Starting in Thunderbird 144, dark message mode will not be activated when in High Contrast mode, respecting the colors and priority of that accessibility setting.

Benefits:

• Consistent use of system colors when in High Contrast Mode
• More respectful of user settings

You can find a complete list of updates and bug fixes that went into Thunderbird 144.0 in our Release Notes.

Thank you for using Thunderbird and for supporting our mission to bring a truly independent, open‑source email experience. Your feedback and enthusiasm drive every improvement we make — and we can’t wait to share more with you in the next release.