Betterbird: Expert Tips

Betterbird is really a Swiss army knife for mail processing. Here are some tips from our project manager to make your experience even better.

New Messages - Activity Manager

Out of the box, when Betterbird starts, it will show you the number of new unread messages and their folders.

If you have many folders an filters, the Activity Manager is also a nice tool to show you to which folders messages were moved. Betterbird opens the Activity Manager in a tab, so it doesn't get in the way. We suggest to keep it always open.

Multi-line view included since September 2021

Many people have asked us to finally implement a multi-line view, so we're happy to announce that this is now included in Betterbird. There are three options:

Language Packs

As of September 2022 we're shipping language packs for the languages we support. Betterbird language packs are specially made for Betterbird to cover its additional functionality. Thunderbird language packs are not compatible with Betterbird. They can't be installed and are are automatically disabled. Language switching after installing Betterbird language packs is available in the user interface provided in the settings.

Custom Icons

On Windows, you can place your custom program icon and your custom icon for the "new mail" notification into C:\Program Files\Betterbird\chrome\icons\default\messengerWindow.ico and C:\Program Files\Betterbird\chrome\icons\default\newmail.ico (assuming the standard installation location).

Here are a few icons to chose from but you can find lots of icon files online. We've included the original icons for you to inspect and modify:

The result looks like this:

Of course you can always configure your desktop shortcuts via the "Change Icon" function.

On Linux, the icons used for the system tray are betterbird/chrome/icons/default/default.svg and betterbird/chrome/icons/default/newmail.svg. Depending on your desktop, other icons are taken from betterbird/chrome/icons/default/default*.png (or /usr/share/icons/hicolor/*/apps).

On Windows and Linux Betterbird also uses msgcomposeWindow for the composw window as well as calendar-alarm-dialog for calendar alarms and calendar-general-dialog for other calendar dialogues as ICO or PNG files. These icons are fixed and will be overwritten with each install. This functionality will ship completely in version 102.11.1 or 102.12.0 onwards.

You can base your own design on these SVG files:


There are thousands of add-on available for Thunderbird which will work 100% the same in Betterbird. Here are the ones we use:

ThunderHTMLedit - great to fine-tune the sometimes erratic HTML the editor produces.

Quick Folder Move - great add-on to find a folder quickly (Shift+G) or move messages (Shift+M).

Shrunked Image Resizer - essential for resizing images before sending.

Signature Switch - great to administer multiple signatures.

Lightning Calendar Tabs - let's you move through the calendar quicker.

Dictionary for recipient - if you write in different languages, store the language you want to use in the address book.

Sender Frequency - adds a column to the message list that lets you determine quickly you writes to you (or spams you) most.

There many excellent add-ons for specific purposes, like Mail Merge, TbSync for access to Exchange calendars, Emoji, Quicktext, FileLink (Dropbox, Box, WebDAV, Nextcloud and ownCloud) and many more.

A word of caution: with add-ons, less is more. Don't overload your system with too many add-ons. Some are poorly maintained or potentially not compatible with the latest application version. Check when the last update was made and handle with care if it's more than a year ago. Actively maintained add-ons will ship updates regularly. We think it's best to find the best add-ons that support your workflow and stick with them.


You can modify the CSS used for the display of the UI by adding a chrome/userChrome.css file to your profile. Use Help > More Troubleshooting Information, select about:profile to locate your profile. You need to set preference toolkit.legacyUserProfileCustomizations.stylesheets to true for changes to take effect. We are using this file (for Betterbird 102), striping ahead.

We're not great friends of customising everything, but this simple theme has stuck with us over the years.


You know that there will be dragons if you mess around too much with preferences, but here is a list of a few useful ones to explore:

Preference, Betterbird onlyFunction
mail.addressDisplayAuthorConfigure address display for mail sender (From): 1 = name, 2 = e-mail, 3 = both
mail.addressDisplayRecipientsConfigure address display for mail recipient (Recipient): 1 = name, 2 = e-mail, 3 = both
mail.biff.show_for_serverSuppress biff notifications for server root folders
mail.multiselect_message_shows_currentShow current message content not message summaries when multiple messages are selected
mail.openpgp.ignore_missing_mdcAllow display of PGP encrypted attachments with missing MDC
mail.startupMinimizedMinimise window after startup
ldap_2.servers.outlook.dirTypeSet to 3 to enable access to Outlook address book (will cause slower startup)
mail.biff.show_tray_iconShow system tray icon when true
mail.biff.show_tray_icon_alwaysAlways show tray icon, even if no unread/new mail
mail.biff.use_new_count_in_badgeTrue/false: Show count of unread/new messages in tray icon
mail.html_sanitize.drop_conditional_cssWhen false, conditional CSS (media queries) won't be discarded
mail.inline_attachments.textWhen true, text attachments are shown inline (recommended)
mail.operate_on_msgs_in_collapsed_threadsWhen collapsed thread is selected, copy/move/delete all messages in thread
mail.override_list_reply_toWhen true (default), overrides the Reply-To header (careful, religious war hiding here)
mail.strictly_mimeWhen true, forces Quoted Printable encoding
mail.ui.display.dateformat.default0: no date, 1: short date, 2: long date, 4: weekday
mail.ui.display.dateformat.thisweekSet to 4 to get "weekday, time" display (recommended)
mail.ui.display.dateformat.today0: no date, 1: short date, 2: long date, 4: weekday
mailnews.default_view_flagsNew folders/views are created unthreaded (0) or threaded (1)
mailnews.display.date_senders_timezoneDisplays the sender's timezone in the header pane
mailnews.display.show_all_body_parts_menuEnables "View > Message Body As > All Body Parts"
mailnews.localizedReList of prefixes that will be treated like Re. Recommended for German: AW,Aw,aw
mailnews.reply_to_self_check_all_identWhen true (default), checks all identities in "reply to self"
mailnews.send_plaintext_flowedWhen false, plaintext won't be flowed (not recommended!)
mailnews.wraplengthLine length used for wrapping, 0 = no wrapping
toolkit.legacyUserProfileCustomizations.stylesheetsEnables userChrome.css when true
ui.prefersReducedMotionControls UI animation, 1 = no animation