TBird v115 ©MJH 2023
(Content modified: September, 2023)
(File modified: June 12, 2024 1:14 pm)
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Michael J. Hannah, Los Ranchos, NM.
Mozilla Thunderbird®
Version 115, Supernova
The Thunderbird open-source email client has undergone a major upgrade with Version 115 called “Supernova”. Its code is essentially being rebuilt from the ground up, which presumably will make the resulting program better, but it will break some legacy customizations and addons to the product. For an explanation of the reasons for the significant change I recommend reading the official blog post on the subject. I actually am pleased with its new focus on the underlying structure being HTML and CSS as I am well versed in HTML and am becoming ever more familiar with CSS. In my opinion this structure will make it easier for users to customize the product to their own tastes. As noted by one of the developers:
“For anyone using the userChrome.css in @thunderbird to customize folder pane and message list, heads up that things will break in 115 because the markup changed and old CSS selectors won't work. The good news is that the new front-end is pure HTML/CSS, so you can open the DevTools to inspect how you want to style and tweak those areas, and even use the DevTools to change the style and see how it looks on the fly. No more obscure XUL markup and strange properties to hunt down!
My main source for information about customizing Thunderbird v115 has been mozillaZine. It is important to recognize that this is NOT an official site. It is strictly run by users for users (so be grateful for any help offered) and there are often users that have already found the customization tweak that you want. The official product sites are part of Mozilla Support: link to various options Contact Thunderbird, Thundebird Support, Thunderbird Support Forum, Mozilla Connect, and bugs need to be officially reported to Bugzilla (where you need a login for which I have been unsuccessful in obtaining).
While I only use Thunderbird for basic email features, I had done some customizations to its “looks” in earlier versions for my own usage. These notes were customizations to version 115.2.0. Much did break, and what follows documents for my own record only those changes I have made to the default functioning of the program. It also describes my very limited discovery of customization features which I recorded here for myself should I want to remember how to make more changes in the future. The following are the general methods, ways, and features I found to customize the product, which in my opinion have decreasing degrees of ease of use, but increasing capabilities to control the program.
• Manual choices from direct menu items when within various windows
• Separate Settings menus for many global configurations
• Built-in Configuration Editor to modify internal settings accessible via Settings
• External CSS styles files to further customize the look, and the Developer Toolbox
• Finally optimize the existing folders to the new file structure
Many choices are considered so common by the developers that they can be adjusted directly on the screen via various mouse actions or menu choices. NOTE: Many of these choices can be reached from more than one menu or method.
• Hamburger menu
• Folder Pane menu
• Message List headers
At the top right of the main screen is the three horizontal line icon generally called the “Hamburger”. When clicked it gives a menu with submenus of choices, four of which I used for my customizations: View, Density, Font Size, and Settings is a choice but is also a choice from the main “Tools” menu, and I discuss it separately below.
Toolbars: I only use the main Thunderbird Menu Bar and the Status Bar
Toolbar Layout…: This can be accessed here but is faster via “Customize…” from a right click on the Thunderbird main toolbar
I set Button Style as “Icons beside text” as it makes the toolbar thinner, although choosing “Text only” would be even somewhat thinner.
My Mail buttons in this toolbar are (in order): Get Messages, Write, Reply, Reply All, Forward, Delete, Junk, Print, Back, Forward, and Quick Filter
Layout: I choose to use the Classic View, and only showing the Folder Pane
Folders: I set All Folders and no others items checked
Folder Pane Header: See below. If this header is hidden this menu option is the way to unHide it.
• Density: is set to Compact at the left
• Settings: this is a choice here but I find it quicker to access from the main “Tools” menu, and I discuss it separately below.
This is an optional header above the list of folders. It has a separate “…” menu when it shows. I choose to “Hide” that header to save space. If hidden see Hamburger/View/Folders to show it again. Two items can each be toggled to appear within the header: the icon for the “Get Messages” action, and a “New Message” button. Since I choose to show the main Thunderbird toolbard, and these buttons exist in it just above the Folder Pane, I find these superfluous. Three menus items toggle showing certain content within the Folder Pane. “Total Message Count” will put the number of the total messages within a folder next to its name. “Folder Size” will show the disk size used by the folder. And if you don’t use “Local Folders” you can hide this entire set of folders. I am not interested in total count or size so hide those, but use local folders so show them. Thus I choose to hide this entire header.
The list of messages in any folder, such as the Inbox, can have various columns of information about each message with a header above the list identifying each column. Which columns are shown can be set to be the same for all folders or unique to a given folder or set of folders. Either a right-click in the headers, or clicking the “Columns” icon at the right side of the headers will display a list to toggle what columns are shown. Once a column is shown its position left-to-right can be changed by “dragging” its header with the mouse. The columns I choose to use (in order) for the Inbox are: Attachments, Read Status, Starred, Subject, From, Recipient, Spam, Size, Date. Once you set the columns for one folder you can copy that set to other folder using the menu itens at the bottom. If you choose “Apply columns…” to “Folder and its children…” where there are many children (such as the folder “Local Folders”), note that when a parent is chosen the name of that parent will be at the top of the list of its children. Selecting the parent will set the columns chosen for all children folders, and their children.
Under the main “Tools” menu is the “Settings” choice. It can also be access by Hamburger/Settings. This opens a new window with tabs for a variety of settings. The following document for my purposes my current settings for each tab area.
System Integration: Always check
Window Layout: (retain) system window titlebar, Auto hide tab
Fonts & Colors: New Century Schoolbook, 10??
Advanced…: (This popup has no content: BUG.)
[See userContent.css below]
Colors…: Use system colors, Underline links, override only with High Contrast
Plain Text Messages: Regular, Regular, black
Date and Time Formatting: Regional
When new message arrive: only show tray icon
Files & Attachments: Always ask me where to save files for all file types
Tags: default [I do not use tags]
Auto mark as read, Immediately on display
Open in an existing message window
Return Receipts: leave in Inbox, allow: Ask me
Updates: check but choose, use background
Connection: System proxy settings
Offline: No auto, remember, no send, no download
Config Editor (This button is the access to this editor, discussed separately below)
Forward: inline, add extension, No auto or add link, Confirm shortcut
Spelling: no checks, English (United States)
HTML Style: Font: Courier, Medium; use Reader's default, not Paragraph
Mail Content: not allow remote content (show notification)
Web Content: not remember or accept, Send “Do Not Track”
Passwords: no Primary Password
Junk: when marked move to "Junk", Mark messages, no logging
Thunderbird Data Collection and Use: none checked
Scam Detection: tell me if spam
Certificates: Ask me, query servers
Email End-To-End Encryption [not used]
[I don’t use this feature, so…]
Styling: Simple, Variant: Normal
I have used this feature in the past by copying my smart phone calendar to my desktop computer, but this still needs some exploration in this new version.
This editor can be accessed by a button at the very bottom of Settings/General to configure a large number of “Advance Preferences”. The best way to find something of interest is to sort on a keyword of some kind, such as “toolbar”. That will filter the list of settings to only those with that keyword in the name. Choosing “Show only modified preferences” will still produce a long list as they will include values automatically changed by the progam as you used it, such as disk.amount_written, or settings for your mail server, etc. I have manually changed the following preferences from the default:
font. … (I have set several preferences in this area, but not all of them seem to work. Need more investigation)
To ensure that external files and some legacy setting work:
toolkit.legacyUserProfileCustomizations.stylesheets: true
To enable the development tools set the following, some are correct by default:
devtools.debugger.remote-enabled: true
devtools.debugger.prompt-connection: false
devtools.inspector.showAllAnonymousContent: true
devtools.browsertoolbox.scope: the word "everything" (no quotes)
Instructions on how to create these files on the forums:
https://support.mozilla.org/en-US/questions/1422908
There are two files which can be built to contain customizations: userChrome.css and userContent.css. “Chrome” [not to be confused with the new browser of that name1] and “Content” are the keywords used to separate the part of the application window decorations (Chrome) from the content web pages and remotely loaded web views (Content). These two files are installed as empty files that can contain CSS elements and values to override the values that Thunderbird would normally use. It’s generally not recommended employing statements in these files because they rely on constructs and keywords which might change easily. However, they do provide complete capability to control the look of Thunderbird in great detail. These files are stored in a Chrome subfolder in the folder on your computer identified by the “Help” menu in the “Troubleshooting Information” as the “Profile Folder”.
There are only a few changes I made to Thunderbird in the userChrome.css file. First I modified the “unread count” of messages which would display after a folder name. I prefer simply black numbers whose background is the same as the folderpane background so all you see is the number. But I set the background of that number to a light blue when the folder contains new messages. Since the overall background, including the background of the unread number, changes (by default) to a darker blue, I set the unread count background to the light folderpane background so the black number is still readable.
Next I vertically compressed the main Thunderbird toolbar as I felt the default took up too much space, and made sure it appeared under the Windows standard toolbar. Finally I vertically compressed the header area of an email message as I thought that also took up too much space.
/* This userChrome.css file is for Thunderbird Supernova */
--folderpane-unread-count-text: black !important;
--folderpane-unread-count-background: var(--color-gray-05) !important;
/* --color-gray-05 is the default folderpane background for Classic */
--folderpane-unread-new-count-background: var(--color-blue-02) !important;
/* these @namespace files are no longer recommended as of v115
@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
@namespace html url("http://www.w3.org/1999/xhtml");
/* If include a hover code, be sure it is above the selected */
#folderTree:focus-within li.selected > .container > .unread-count {
background-color: var(--color-gray-05) !important;
/* Compress the TBird main toolbar */
padding-bottom: 0px !important;
/* be sure Windows toolbar is above TBird toolbars */
/* put the TBird main toolbar under the Windows toolbar */
/* Compress the header on an email message */
.message-header-extra-container {
Finally I needed to add statements to the userContent.css file to modify the font and size of text within an email message’s content. There appears to be a current bug
/* This userContent.css file is for Thunderbird Supernova */
* { font-size: 12px !important; }
:root { --MJH-test-variable: rgb(0, 0, 0); }
/* modify the Plain Text font and size */
@-moz-document url-prefix("imap:"),url-prefix("mailbox:"),url-prefix("news:") {
font-family: Courier !important;
Hamburger/Tools/Developer Tools or Tools/Developer Tools/Developer Toolbox or Ctrl+Shift+I
https://forums.mozillazine.org/viewtopic.php?f=39&t=3075977
Create a folder called distribution where the thunderbird.exe is located and place a policies.json file there, then restart:
* <installation directory>\distribution\policies.json
Content of the file should be:
To test if the DisableAppUpdate policy is working:
Outlook, gmail, yahoo have deprecated basic username/password authentification, and are now requiring OAuth2 authentication. SMTP authentication has been restricted or in some cases, completely disabled. These providers require permission to place cookies for OAuth2 to work smoothly. Here's what worked for me:
1. In Thunderbird, Settings, Privacy and Security, tick "Accept cookies from sites", including "Accept third party cookies". Outlook and gmail require this.
2. In Thunderbird, Tools, Account Settings, set the Authentification method to OAuth2.
3. Next, follow exactly the instructions given on the Mozilla support site, at the link here: https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202 . The relevant part is number (2) on the list: "use the config editor to filter for "oauth2", find the appropriate server(s), and delete the entries for "oauth2.issuer" and "auth2.scope".
More info about the Config Editor can be found here: Config Editor (explicit path: https://support.mozilla.org/en-US/kb/config-editor)
3. Restart Thunderbird and provide the passwords for your accounts in the pop-up windows as prompted.
Outlook and gmail accounts throw out big, white pop up windows, where you need to log in then click YES to allow Thunderbird to access them. They look like this: https://answers.microsoft.com/en-us/outlook_com/forum/all/managing-apps-and-services-connected-to-ou...
Do this for each account to make it compatible with the new authentication protocol of outlook or gmail. It will then send and receive mails through Thunderbird again
Immediately after converting I found downloads from an IMAP server to be extremely slow. Several on-line posts suggested the following steps which did greatly improve performance. I am “guessing” that this is caused by some new file structure but with remaining (slow) code which deals with any old folders with legacy structure. Whatever, these steps seem essential for adequate performance.
Endnotes
1. userChrome.css is much older a filename in the Netscape/Mozilla history than the browser Chrome. So one should ask, why Google named a browser after a part of another browser instead of asking why "Chrome" is part of that filename.
Disclaimer
I do not warrant in any way that this document is accurate or useful, or the results would be the same in another version of Thunderbird, and any use of it is at the user’s own risk.
As described in a separate document, this document was composed with Adobe® FrameMaker 2019®, converted using its hyperlink and "Save as HTML" features, post-processed with my custom Perl© script, linked to my Responsive CSS file, and the HTML and CSS are W3C validated.
©MJH Consulting, 2023. All rights reserved.
(Content modified: September, 2023)