halo.spaces

A calm, tidy Mac look for Mozilla Thunderbird.
Mail, Calendar, Contacts, Tasks and Chat in one quiet design, with the details that make a mail app feel at home on macOS.

Download the latest version  ·  Installation  ·  What's new

halo.spaces is one package for Thunderbird 153 or newer: the design, its own clean icons and an extension for everything a theme alone can't do. Install it, and Thunderbird looks and feels different right away. No restart, no userChrome.css, no settings to hunt for. Updates arrive automatically.

All screenshots show made-up test data.

Every message gets a round sender picture, automatically:

• the photo from your address book,
• or from the Contacts app on your Mac (optional),
• the company's official BIMI logo,
• the icon of the sender's website,
• otherwise coloured initials.

The list shows calm message cards with a two-line preview, time, star and paperclip. Unread mail can get a light accent tint, replied and forwarded mail a small arrow. Prefer columns? Switch to a classic table in one menu.

• Light and dark follow macOS, the accent colour follows your system
• Coloured spaces on the left: Mail, Contacts, Calendar, Tasks and Chat, all with the same toolbar and sidebar edges
• Its own icons throughout: toolbar, folders, menus
• No scrollbars: scrolling still works with wheel, trackpad and keyboard
• Sidebars slide in and out; drag a divider all the way to close a sidebar, double-click it to reset
• Questions appear as a sheet at the top of the window, dialogs without a title bar
• Messages in the system font; respects Increase contrast in the accessibility settings

The Today pane runs to the top of the window and stays the same in every space:

• the current weather as the symbol next to the title, for your city or your location (optional, data from Open-Meteo)
• a mini calendar
• an agenda card up to the end of the month, with "now" and "in 2 hr" for upcoming events
• a button for a new event right in the header

The search field sits top right, like on the Mac:

• results from Thunderbird's index appear instantly, also matches only in the message text
• a background search then checks the folder and adds mail that isn't indexed yet, without duplicates
• it searches the selected folder, or all mailboxes from a unified folder such as All Inboxes
• the header shows where you are searching and how many results there are
• scrolling through results stays smooth even while a long search is still running

• Undo Send: take a message back for a few seconds after sending (time adjustable)
• Send Later: tonight, tomorrow morning or a time of your choice, from the arrow on the send button
• Remind Me: the message comes back unread in an hour, tonight, tomorrow or next week
• Follow Up: a gentle note about your own messages that got no reply
• Whole conversations: received mail and your own replies from Sent, newest first
• Filter menu: hold or right-click the filter button for Unread, Starred, Only from Contacts or Only with Attachments
• Quick Look for attachments: press the space bar in the attachment list or choose Quick Look from its menu (macOS, Thunderbird 158 or newer)
• Mailing lists show a quiet note with Unsubscribe, which disappears once you're out
• Unified inboxes, Inbox always first
• A calm writing window: symbols-only toolbar, round send button, format bar on demand, attachments as tiles
• Encryption at a glance: a clear lock while writing, a quiet lock and seal on encrypted or signed mail

• Day, Week, Multiweek and Month switcher in the title bar, a month view without scrollbars
• Quick event window: just type, "tomorrow 12:30 for 90 min" or "Fri 9 to 11"; repeat and alerts with custom rules; a double-click in the calendar opens it too
• A clear event window with cards for time, location, invitees and calendar, and date and time in one popover
• Emojis before event titles (birthday, dentist, training …), with your own keywords
• Birthdays from your address books as their own calendar
• Tasks as a list with details on the right, filters in a menu
• Calm reminders with a calendar icon showing month and day

• All address books in one list, duplicates merged, account labels in the account colours
• Contact photos with a round crop and zoom slider
• Cards with name or company only, the details on the right

• Drag a space up or down in the spaces bar to reorder it, the others move out of the way
• Don't use Chat? Replace it with the space of another add-on, for example your favourite chat or notes add-on, or with a website you keep open all day, or with nothing at all
• A short welcome after installing asks about weather and Chat, everything else just works
• All options in one place: Settings → halo.spaces, next to Account Settings and Add-ons, and found by the settings search

1. Download the latest halo-spaces-<version>.xpi from Releases.
2. In Thunderbird open Add-ons and Themes → gear icon → Install Add-on From File… and choose the file.
3. That's it. The design is active right away, no restart needed.

On first install halo.spaces sets Themes to System theme – auto (Thunderbird's default), so light and dark follow macOS. Thunderbird's Light or Dark stay if you chose one; themes from the add-on store paint their own colours over the design.

Updates arrive automatically (Thunderbird checks every 24 hours). To check right away: Help → halo.spaces… → Check for Updates.

No userChrome.css is needed. An older copy of this theme in your profile's chrome folder takes precedence and would hide updates, so remove it.

Options that belong to a view are set right there: preview lines under View → Preview Lines, contact photos in the list's … menu, and the Birthdays calendar with its checkbox in the calendar list. Everything else is in Settings → halo.spaces (also via Help → halo.spaces… → Settings…). Changes take effect right away unless noted.

• Sidebars make room on their own: when the window gets too narrow, for example after opening the Today pane on a laptop, the sidebar of the current space slides away first, then the spaces bar, with the same animation as their buttons. Widen the window and they come back. A sidebar you hid yourself stays hidden; if you show it again, the Today pane makes room
• Archive an account locally: right-click an account and choose Archive Account Locally… to copy all its folders to Local Folders, for example before a school or work account expires. Trash, Spam and Drafts are left out; running it again only adds what is missing
• Outlook data files (PST): File → Open Outlook Data File (PST)… reads a PST file and shows its folders with the number of messages. Importing the messages follows in a later version
• Toolbar: when a wide button has to make room, a narrower one comes back if it fits, so the search field stays small and more buttons stay visible
• Fixes: clicking the "Today" heading in the Today pane now really jumps to today, and double-clicking it no longer zooms the window; the tooltips of the heading and the weather show up again; after widening the window there is no empty gap next to the message list; the address book list no longer sticks out over its column while it slides in or out
• Requires Thunderbird 153 or newer

See Releases for all versions.

• Made for macOS. Windows and Linux work, but they aren't the focus. Window buttons and some spacing differ there, and you'll see a short note on first start.
• The compose window and a few dialogs are only partly themed.
• Report issues via GitHub Issues. Please include your OS, Thunderbird version and a screenshot.

halo.spaces has no server, no account, no analytics and no telemetry, and it never sends your messages, contacts or events anywhere. It only goes online for what you see: sender logos (the sender's domain only, can be turned off), the weather if you turn it on, a website you chose as a space, and update checks. Details in the privacy policy.

./build.sh                       # → dist/halo-spaces-<version>.xpi (includes theme.css)
python3 tests/halo_test.py       # automated checks in a fresh, temporary profile
./release.sh 3.1.0               # version, update URL, runs the tests, writes updates.json
./publish.sh 3.1.0 notes.md      # uploads exactly that package and verifies the hash

halo.spaces uses the coffee cup from Noto Emoji (© Google LLC, Apache License 2.0), see extension/about/NOTICE.txt. The optional weather in the Today pane uses data from Open-Meteo.com (CC BY 4.0). The layout of this page started from FluentBird by Danny King.

Released under the Mozilla Public License 2.0.

Questions or feedback? In Thunderbird: Help → halo.spaces… → Send Feedback, or open an issue here. Enjoy!