Firefox 153 contains itself while Thunderbird 153 fixes almost everything

Mozilla recently released Firefox 153, followed shortly by Thunderbird 153, both known as Extended Support Releases (ESR). Firefox 153 provides security updates until after the next ESR in mid-2027. Among the enhancements in this version is a preview of Multi-Account Containers, which enables users to separate sets of settings and credentials more easily. For mobile users, Firefox 153 for Android now includes tab groups, while iOS users in the US have access to the new Quick Answers feature.

Thunderbird 'Meadow' MZLA's Thunderbird version, also an ESR, was codenamed "Meadow." The release notes highlight 32 refinements, 15 changes, and 181 bug fixes, suggesting a significant update for the ESR release. Among the improvements are updates to folder handling, notifications, OpenPGP encryption, OAuth login, address book export, PDF handling, and more.

Notably, Thunderbird is dropping 32-bit Linux binaries, joining Firefox in doing so after Firefox 144. Additionally, the term "Junk" mail has been changed to "Spam," and the setup option for the Russian Odnoklassniki service has been removed in favor of XMPP configuration.

Users may find the variety of views in Thunderbird confusing, but several non-default views have been improved. The "Unread Folders" view now better hides folders with no unread messages, while the "Unified Folders" view lets users color-code different accounts. Thunderbird is also introducing support for Thundermail accounts, part of MZLA's paid email service, Thunderbird Pro. This suggests that the paid service is nearing launch.