Firefox 153 contains itself while Thunderbird 153 fixes almost everything
Mozilla has released Firefox 153, a new Extended Support Release (ESR), alongside MZLA's Thunderbird 153, codenamed "Meadow." Firefox 153 will receive security updates until sometime after the next ESR, expected in mid-2027, and brings a notable new feature: built-in support similar to the Multi-Account Containers extension, letting users separate credentials and sessions (for example, "home" versus "work" logins) without needing add-ons. The update matters because it consolidates a popular privacy and organisation tool directly into the browser, while also extending support to older platforms still running legacy ESR builds.
Beyond containers, Firefox 153 for Android adds tab groups, and Firefox for iOS users in the US get a new on-device speech-recognition "Quick Answers" feature, though queries are still sent online to generate responses. Thunderbird 153 is a much larger update, with 32 refinements, 15 changes and 181 bug fixes, covering folder handling, notifications, OpenPGP encryption, OAuth login, address book export and PDF handling; it also drops 32-bit Linux builds and renames "Junk" mail to "Spam." Separately, older ESR branch Firefox 115 was updated to 115.38 for users still on Windows 7–8.1 and macOS 10.12–10.14.
In short
- Firefox 153 and Thunderbird 153 ("Meadow") ESRs released
- Firefox 153 adds built-in container-style account/credential separation
- Thunderbird 153 ships 181 bug fixes and drops 32-bit Linux support
Explained simply
Firefox is a web browser and Thunderbird is an email client, both made by Mozilla, a not-for-profit organisation dedicated to open-source software. Millions of people worldwide rely on these tools daily for browsing the web and managing email, particularly those prioritising privacy and user control. New versions of these applications matter because they affect how millions interact with the internet and manage their digital communications.
Extended Support Releases, or ESRs, are specific versions designed for users who prefer stability over frequent updates and receive long-term security patches instead. Firefox 153 is Mozilla's latest ESR and will receive security updates until mid-2027, making it attractive to both individual users and organisations wanting consistent, predictable software support. This approach explains why different users choose different release versions based on their needs.
Mozilla has increasingly moved to incorporate popular features directly into its browsers and email client rather than relying on add-ons, reflecting how user needs and privacy concerns are shaping software development. Both Firefox 153 and Thunderbird 153 continue this trend, consolidating requested features and fixing accumulated issues to improve user experience. Understanding this pattern helps explain why regular updates remain important even as software matures.