A new major version of the email client Thunderbird will be released later today that brings the version of the program to Thunderbird 60.0.

While August 6, 2018 is the release date, Thunderbird 60.0 won't be offered through the email client's automatic updating system on that day. The Thunderbird team did not reveal why Thunderbird 60.0 is only offered as a direct download at this point in time.

One explanation is that users may run into updating issues with the built-in Lightning calendar component of Thunderbird. The team published a FAQ page that answers questions related to that.

Users who are interested in upgrading to the new version can download it from the official project website Thunderbird.net and install it manually. Note that the new version is not yet listed on the official site but that it will be later today.

System Requirements changes: Thunderbird 60.0 dropped support for Windows XP, Windows Vista, and the server versions of Windows. No change for Linux and Mac versions of the program. In other words: Thunderbird runs on Windows 7 or newer on the client side, and Windows Server 2008 R2 or newer on the server side only.

Thunderbird 60.0

We reviewed Thunderbird 60.0 Beta when it was first released. It may be a good idea to revisit the article and read it if you have not done so already as it gives you a good overview of all of the changes in Thunderbird 60.0.

The following paragraphs provide you with the most important information about the new release, and other changes. You may want to consult our beta overview and the official release notes to get the full picture.

Important change regarding Extensions

Thunderbird users who run extensions that are not explicitly marked as being compatible with Thunderbird 60.0 will notice that these get disabled on first start due to strict compatibility enforcement in the release.

It is possible to override this in Thunderbird 60.0 in the following way:

1. Select Tools > Options from the Thunderbird menu.
2. Go to Advanced > General.
3. Activate the Config Editor button on the page.
4. Search for extensions.strictCompatibility
5. Double-click the preference.

A value of true is the default and means that Thunderbird enforces strict compatibility. Any extension that does not state in its manifest that it is compatible with Thunderbird 60 won't be loaded by the email client.

Setting the value to false disables the compatibility check in Thunderbird. Extensions that are compatible with Thunderbird 60.0 but not marked as such by their authors (for instance because they have been abandoned) will run fine afterward.

Note that the setting can't enforce compatibility magically if extensions are indeed incompatible.

Other changes of note

• Support for FIDO U2F and OAuth2
• Password can contain non-ASCII characters.
• Calendar improvements
• Attachment improvements, e.g. reordering.
• Support for WebExtensions themes.
• Light and Dark themes support.
• Photo design bits implemented similar to those in Firefox.
• Native notifications on Linux.
• Thunderbird uses Rust-based modules for displaying and encoding messages, and other parts of the program.
• Change the spellcheck language from the status bar.
• New Message from Template option.
• The update interval of feeds can be set individually.
• If storing sent IMAP messages fails, those messages may be saved locally now.
• Other IMAP fixes
• Handling of IMAP trash folders.
• Rare cases of sending IMAP messages with the wrong identity.
• Shared IMAP folders not shown in subscribe dialog under certain circumstances.
• Missing messages that were moved between IMAP accounts.
• Add-on options need to be configured under Tools > Add-on Options now.

Closing Words

Thunderbird 60.0 is a massive release. It may be best if you test the release before you update existing installations of Thunderbird to the new version, for instance by copying the Thunderbird profile to a new computer, user account, or virtual machine installation of Thunderbird.