This article describes some of the major changes visible to users in Thunderbird version 68.0. Full details of all the changes can be found in the Thunderbird 68 release notes.
Table of Contents
New App Menu
Thunderbird 68 features a big update to the App Menu. The new menu is single pane with icons and separators that make it easier to navigate and reduce clutter. Animation when cycling through menu items produces a more engaging experience and results in the menu feeling more responsive and modern.
Options/Preferences in a Tab
Thunderbird's Options/Preferences have been converted from a dialog window to its own dedicated tab. The new Preferences tab provides more space which allows for better organized content and is more consistent with the look and feel of the rest of Thunderbird. The new Preferences tab also makes it easier to multi-task without the problem of losing track of where your preferences are when switching between windows.
Full Color Support
Thunderbird now features full color support across the app. This means changing the color of the text of your email to any color you want or setting tags to any shade your heart desires.
Better Dark Theme
The dark theme available in Thunderbird has been enhanced with a dark message thread pane as well as many other small improvements.
There are now more options available for managing attachments. You can "detach" an attachment to store it in a different folder while maintaining a link from the email to the new location. You can also open the folder containing a detached file via the "Open Containing Folder" option.
Filelink attachments that have already been uploaded can now be linked to again instead of having to re-upload them. Also, an account is no longer required to use the default Filelink provider - WeTransfer.
Other Notable Changes
There are many other smaller changes that make Thunderbird 68 feel polished and powerful including: an updated To/CC/BCC selector in compose, filters can now be set to run periodically, and feed articles now show external attachments as links.
There are many other updates in this release, you can see a list of all of them in the Thunderbird 68 release notes.