Mozilla Thunderbird, the popular open source email client, launched recently his version 134, focused on incorporating new functionalities, correcting existing errors and strengthening user security. This update is especially relevant for those looking for an efficient and reliable client to manage emails, calendars and tasks on different platforms.
Thunderbird 134 arrives with a combination of new features that seek improve both functionality and user experience. Among the highlights is a new real-time notification system that makes it easier to stay on top of new messages without having to open the app repeatedly. In addition, adjustments have been made to the interface and internal processes to offer smoother and more efficient handling.
Key New Features in Thunderbird 134
Version 134 introduces several features that cement Thunderbird as a robust alternative among email managers:
- Real-time notifications: Now, users will receive instant alerts on your desktop every time a new email arrives, improving multitasking and instant response.
- Bug fixes: Fixed issues related to app launch, account authentication, and data synchronization with CalDAV calendars, as well as other minor bugs in the XMPP chat system and handling of large virtual folders.
- Notification customization: Users can adjust how they receive alerts, choosing from options such as sounds, banners or pop-ups, tailored to their personal preferences.
- Graphical and usability improvements: Adjustments to dark mode and button layout to make the interface more consistent across different operating systems.
- Support for new features: It is now possible to drag embedded images from an email directly into a compose window, improving integration with other tools.
Relevance in Security
In addition to the mentioned functionalities, Thunderbird 134 has put a strong emphasis on mitigating critical vulnerabilities. Among the nine security fixes included in this release are:
- CVE-2025-0237: Fixes a flaw in permissions validation to reduce risks of privilege escalation.
- CVE-2025-0244: Addresses issues that allow external attackers to perform spoofing via the address bar in derivative browsers.
- CVE-2025-0245: Improves protection against unauthorized access to locked settings.
- CVE-2025-0242: Fixes issues associated with memory corruption, reducing the risk of remote malicious code execution.
These improvements not only prevent attacks, but strengthen Thunderbird's overall environment as a trusted tool for businesses and home users.
Fixes and Issues Resolved
This update addresses several bugs that were reported by the community. Fixed issues include:
- A recurring crash when launching Thunderbird on POP3 systems.
- Mismatches when downloading message headers in newsgroups.
- APOP authentication problems in POP3 email accounts.
- Visual bugs in dark mode, such as misalignment of buttons on in-app notifications.
- Failures when replying to emails using specific contextual functions.
How to Upgrade to Thunderbird 134
Mozilla has made the upgrade process easier to ensure that all users can take advantage of these improvements immediately. It is recommended that you:
- Update directly from the application, accessing the menu "Help" and selecting “About Thunderbird”, where the update will be downloaded automatically. That's if you're using binaries or are on Windows and macOS systems. Enable automatic updates to make sure you don't miss future security fixes.
- Download the latest version from the official Thunderbird website, selecting the latest version available for your operating system.
Linux users using the official repository version will have to wait for their distribution to upload the new packages.
Those already on older versions, including Extended Support Releases (ESR), should also consider this update as a priority for shield your digital security.
Thunderbird 134 not only fixes bugs and strengthens its architecture, but also introduces significant improvements to optimize the daily user experience. This release reinforces Thunderbird's position as one of the most more robust email clients and accessible, adapting to the needs of a diverse public and guaranteeing high safety standards at all times.