There is also a 64-bit version of Thunderbird, but it is hardly mentioned. Thunderbird 60.0 is available for Windows 7/Windows Server 2008 R2 and newer(Windows XP and Windows Vista as well as older server versions are no longer supported), Linux and macOS.

That's why I'm reluctant to upgrade, especially since it should take some time before a portable version is available. The team has published a FAQ page that answers questions. One explanation, according to Martin Brinkmann, is that users may have problems updating with the Lightning Calendar component built into Thunderbird. The Thunderbird team did not explain why the Thunderbird 60.0 is only available as a direct download at this time. Window: Windows 7, Windows Server 2008 R2 or later.Refer to this troubleshooting article in case of problems. If you have installed Lightning, Mozilla's Calendar add-on, it will automatically be updated to match the new version of Thunderbird. Thunderbird version 60 is currently only offered as direct download from and not as upgrade from Thunderbird version 52 or earlier. Users need to download the new software and install it. A manually initiated search for an update will also show that the client is up to date. Thunderbird 60.0 has been released August 6, 2018, but the new version 60.0 of Thunderbird will not be available through the email client's automatic update system. Thunderbird 60.0 is a new major version (currently I'm using Thunderbird 52.9.1). I have already been informed about the new Thunderbird 60 by mail from German blog reader Gero S., but I had already seen it at Martin Brinkmann.

Mozilla thunderbird update 2018