Mozilla releases Thunderbird 78.7, an application update that includes a number of general fixes and new API improvements. It is now available for download for Windows, Mac OS and Linux.

Thunderbird is my favorite e-mail program. I use this application on every computer and operating system I use. It is stable, contains all necessary functionality, supports add-ons and comes with a handy RSS reader. I have been using Thunderbird for years and have never felt the need to look for an alternative.

Thunderbird 78 no longer supports the classic XUL add-ons, but does include some of their out-of-the-box capabilities. In Windows, for example, you can minimize an application on the taskbar.

The following amendments were made to the Annex.

What happens in Thunderbird 78.7.

New and updated API extension

  • New API extensions : Link API now allows you to edit posts and templates as new posts
  • ⭐New API extension: composeHtml is now available in MailIdentity.
  • ⭐New API extensions: windows.update and windows.create now support titlePreface.
  • ⭐New API enhancements: new accounts API functions: accounts.getDefault() and accounts.getDefaultIdentity(accountId).
  • API extension updated: body and plainTextBody are now used as formatting mode selectors in the setComposeDetails and start* functions in the Compose API.
  • API extension update: Browser action buttons are not restored after a restart if they are moved outside the default toolbar.
  • Update of the extension API: browser.compose.beginNew could not replace the plain text parameters of the identifier
  • API extension update: browser.compose.beginForward ignores ComposeDetails.
  • Update to the API extension: browser.compose.setComposDetails does not correctly handle Windows lowercase style endings.


  • Account Manager : When the last remaining account was deleted, the default account was not deleted and continued to point to a non-existent longer account.
  • OpenPGP : Checking a message signed as a string fails if it contains leading spaces.
  • OpenPGP : Various other minor stability bugs and fixes
  • Post window : The buttons on the quick filter bar disappear when the mouse pointer hovers over the Windows 10 Contrast Black theme.
  • Subject: The folder properties dialog box contains black text on a black background in dark mode.
  • Subject: The tablet receivers in the composition window were not visible in Windows 10’s dark, high-contrast theme
  • API extension: the browserAction buttons are not restored after a restart if they have been moved outside the default toolbar.
  • API extension: browser.compos.beginNew can not overwrite identity parameters in plain text
  • API extension: browser.compose.beginForward ignore ComposeDetails
  • API extension: browser.compose.setComposDetails does not correctly handle lowercase Windows style.
  • Various security patches
  • Download Thunderbird

Download Thunderbird

Information about this version can be found here.

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Sergei Tkachenko on January 27, 2021 in the program.

About Sergei Tkachenko

Sergey Tkachenko is a Russian software developer who founded Winaero in 2011. In this blog Sergey writes about everything related to Microsoft, Windows and popular software. Follow him on Telegram, Twitter and YouTube.

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