Not all extensions will be supported in Thunderbird 68

[tarekma7]

While Thunderbird 60.7.0 will be released later today, work continues on the next major release of the email client, Thunderbird 68.0.

Thunderbird development is closely tied to the development of Firefox ESR. Firefox 68.0 ESR will be released on July 9th, 2019 and Thunderbird 68.0 will be released shortly thereafter.

The move to a new ESR base introduces a huge number of changes. Extended Support Release versions of Firefox or Thunderbird get security fixes and major bug fixes first and foremost for as long as they are supported. All other changes introduced to regular versions are implemented during switches to new major versions.

Thunderbird 68.0 is such a switch and one of the major changes of that release is that extension support will be affected negatively by it.

If the Thunderbird team would not have done anything at all, only WebExtensions would be supported by Thunderbird 68.0. All classic extensions would not work anymore and there would have been nothing that users could do to change that.

The Thunderbird team decided to bring back some support in Thunderbird 68.0. Considering that Mozilla purged lots of important code needed to run classic extensions, it is probably the best the team could do with its limited resources.

The Waterfox browser uses the same code to support some legacy extensions in the upcoming Waterfox 68 release. A first alpha of Waterfox 68 was released recently.

The limitations

Thunderbird 68.0 will support WebExtensions and the following types of extensions:

Restartless add-ons if "minor adjustments" were made by their authors.
Non-restartless legacy add-ons using XUL overlays if add-on authors adopted them.
Some extensions have been modified already including the built-in Calendar Lightning, ThunderHTMLedit, Compact Header, Signature Switch, and Send Later.

As far as dictionary support is concerned, only WebExtension dictionaries are supported when Thunderbird 68.0 is released. WebExtension directories are available on Mozilla's and Thunderbird's add-ons repository websites.

SOURCE