Thunderbird 153 “Meadow” has been released, introducing native Microsoft Exchange support alongside a redesigned account setup experience, user interface improvements, and security fixes.
The update marks the first time Exchange accounts can be configured directly in Thunderbird without relying on third-party add-ons.
Mozilla describes Thunderbird 153 as the culmination of the features and refinements introduced through the Monthly Release channel over the past year. The release focuses on improving onboarding, expanding enterprise compatibility, and refining the overall user experience.
Thunderbird is Mozilla's free and open-source email client, used by millions of individuals, businesses, and organizations across Windows, macOS, and Linux. It supports multiple email providers and protocols, making it a popular alternative to proprietary mail clients such as Microsoft Outlook.
Exchange support
The headline addition in Thunderbird 153 is native support for Microsoft Exchange email servers through Exchange Web Services (EWS). Until now, users who wanted to connect Thunderbird to on-premises Exchange deployments or compatible Exchange environments typically had to install extensions such as Owl or ExQuilla. With version 153, Exchange accounts can be added directly through Thunderbird's built-in account setup process, allowing users to read, compose, organize, and manage Exchange email without additional software.
Mozilla also revealed that support for Microsoft Graph has already been integrated into Thunderbird's codebase but remains disabled by default while development continues. Full Microsoft Graph support, including Exchange Online calendar and address book synchronization, is planned for later this year, providing a future migration path as Microsoft continues moving customers away from Exchange Web Services.
Another major change is the introduction of the new Account Hub, which replaces Thunderbird's previous account setup workflow. The redesigned interface automatically detects supported email protocols via auto-discovery, configures compatible accounts, and discovers associated calendars and address books. Mozilla says the new setup process significantly reduces the number of manual configuration steps required when adding new accounts.
The update also expands address book management by allowing users to configure both local and remote address books from the same interface. Existing email accounts are automatically scanned to identify directory services that have not yet been configured, simplifying deployment in enterprise environments.
Native operating system notifications have also become more interactive. Users can now perform common actions directly from notification pop-ups, including marking messages as read, deleting emails, or reporting spam without first opening the application.
Additional improvements include OAuth authentication through the user's default web browser instead of embedded login windows, one-click authentication for Thunderbird accounts, an improved folder sorting interface, and thousands of bug fixes and performance improvements accumulated over the past year.
Mozilla also addressed dozens of vulnerabilities in Thunderbird 153. While most browser engine flaws are not exploitable via email because scripting is disabled when reading messages, the release patches numerous high-severity issues, including memory safety vulnerabilities that could be exploited to execute arbitrary code. Other fixes address privilege escalation, sandbox escape, information disclosure, and denial-of-service vulnerabilities inherited from Firefox's underlying platform.
Thunderbird 153 is available immediately as a manual upgrade through Help > About Thunderbird or as a direct download from thunderbird.net for Windows, macOS, and Linux. Automatic updates will be rolled out gradually as Mozilla monitors the stability of the release, while Snap, Flatpak, and Microsoft Store versions are expected to become available over the coming weeks.
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