While newer versions are available, you can still access the specific Thunderbird 91.0 release for various operating systems:
For those on Windows, you can find installers such as the Thunderbird 91.0.1 64-bit installer on Filepuma. thunderbird 91.0 download
The most reliable way to obtain this specific version is through the Mozilla Archive . While newer versions are available, you can still
Improved contact management through native CardDAV address book support and auto-detection. While newer versions are available