Hands On: Mozilla Thunderbird Spreads Its Wings Anew With ‘Supernova’ Release

After years of intermittent development that at times left Mozilla Thunderbird(Opens in a new window) looking more like Mozilla Pteranodon(Opens in a new window), a major update to this open-source offshoot of the Mozilla Firefox browser makes a renewed case that a standalone mail client doesn’t have to be a dinosaur.

The version 115 “Supernova” edition of Thunderbird, shipped Tuesday for Mac, Windows, and Linux, brings what a blog post(Opens in a new window) calls “a modernized overhaul of the software—both visually and technically.” It also represents the first public deliverable in the campaign to rewrite that app and retire years’ worth of technical debt that Thunderbird announced in February.

Thunderbird’s new ‘Card View’ layout (Credit: Mozilla)

As installed on a Windows 11 laptop (a Lenovo ThinkPad x13s with a Qualcomm Snapdragon chip) and set up to access an intensively used Google Workspace account, the new Thunderbird didn’t initially look that different from the old version at first. 

To start, it presented that account in its “Classic” view(Opens in a new window), in which a message preview pane sits below a message list, instead of the new “Card View” layout, where one vertical pane shows a two-line preview of each message while a message pane at its right shows the selected message. 

Next, Thunderbird’s new “AppMenu”—a shortcut to the most important settings—was easy to miss behind a small hamburger menu icon, set off to the right of the large search box that gets more prominent display in the new “Unified Toolbar.”

I also had to wait to play around with some of these options, because the app got bogged down while ingesting the tens of thousands of messages in the inbox alone. 

(Credit: Mozilla)

Thunderbird’s built-in calendar app (formerly a feature that required you to install a separate extension) also gets some attention in the new release. It now provides a “mini-month” view of your calendar that puts a dot on every date that has an event happening—which, if your calendar is as crowded as mine, may not reveal anything useful. 

The address book seems to have received the fewest tweaks in this update, perhaps because the previous release brought significant changes to a component(Opens in a new window) that early on ranked as one of Thunderbird’s most inadequate parts(Opens in a new window). 

Thunderbird’s blog post promises more to come in what that organization described in February as a multiple-year journey: “Throughout the next year, we’ll deliver many improvements to existing Supernova features and introduce brand new ones, including Thunderbird Sync.”

Thunderbird or Outlook?

Microsoft, meanwhile, already offers its own mail-contacts-calendar app, Outlook, for Office purchasers and Microsoft 365 subscribers, while Windows 11 ships with separate Mail, People, and Calendar apps. But because both the paid and free options work so poorly with Google Calendar, Outlook is still limited out of the box to read-only sync to a Google account(Opens in a new window) while the free Calendar app doesn’t let you set time zones for an appointment(Opens in a new window).

Microsoft is now readying a new built-in mail/contacts/calendar app for Windows(Opens in a new window)—which it’s calling Outlook, not to be confused with the old Outlook or the web-based Outlook.com(Opens in a new window)—that does let you view and edit events on a Google-hosted calendar in all of their time-zone complexity.

As Microsoft moves to make that app the new normal for Windows home users (for instance, opening the old Calendar app on the test Windows 11 laptop surfaced an invitation to try the new Outlook), that may put Thunderbird on a steeper slope. 

The biggest competition for this any other new email client will probably remain the option that normally lives in the first tab open in any browser: the standard web-app view of Gmail or another web-first mail service, even if it’s full of ads and glitches every time your connection hiccups.