Mozilla did not just patch Firefox this month, Thunderbird also got its regular update, rolling out version 147.0 and the long-term support 140.7 ESR. Think of this as a maintenance + QoL patch: security fixes, crash prevention, and a couple of nice usability upgrades that smooth out daily play.

Stability First: Fewer Crashes, More Reliability

Both versions focus heavily on security fixes and crash issues, making Thunderbird more stable under heavy load. The detailed crash fixes are mostly listed under the 147.0 patch notes—but the ESR build benefits too, keeping long-term users safe and steady.

New Features: Small Changes, Big Comfort

Full Folder Path Visibility (Compact View)

A new "Show Full Path" option has been added to the folder pane when using compact view modes. Translation: no more guessing which folder you’re in when you’re deep in a nested hierarchy. This is a huge quality-of-life upgrade for users with complex setups.

Folder Name Localization Toggle

A new setting, mail.useLocalizedFolderNames, lets you turn localized special folder names on or off. If you prefer clean, consistent naming instead of language-based variations, this gives you full control.

Changes: Smarter Folder Localization

Thunderbird now localizes special folders using a restricted list of known folder names. This reduces confusion, prevents mismatches, and makes folder behavior more predictable. especially useful if you sync across multiple devices or servers.

Fixes: A Massive Bug Squash

This update absolutely goes to town on bugs. Highlights include:

• Fixed folder compacting failing when multiple folders were selected

• Resolved broken manual folder sorting for subfolders

• Fixed unified archive folders showing wrong names or missing messages

• Prevented crashes when marking all messages as read

• Fixed startup slowdowns when managing huge folder lists

• Resolved IMAP, EWS, and SMTP issues that caused hangs, errors, or crashes

• Fixed OpenPGP “Open and Show” not working for signed .eml files

• Repaired broken search behavior across settings and messages

• Fixed calendar alerts not triggering during connection issues

• Restored task creation with Start or Due dates

• Fixed Japanese locale filter creation issues

• Numerous visual and UX polish improvements

In short: less freezing, fewer crashes, faster startup, and smoother workflows, especially if you are managing lots of accounts or folders.

Thunderbird 147.0 is not about flashy new features, it is about making sure everything just works. If you rely on Thunderbird daily, especially with large mailboxes, IMAP setups, or Exchange accounts, this update is a must-install.