: It included critical security updates that originally shipped in Thunderbird 102.2.1 to provide a safer experience for legacy users. System Requirements
: You can find all installers (Windows, macOS, and Linux) in the Mozilla Release Archive . thunderbird 91.13.1 download
: For a version that runs from a USB drive without installation, use the PortableApps.com Legacy 91 version. Key Fixes in Version 91.13.1 : It included critical security updates that originally
is a legacy version of the popular open-source email client developed by the Mozilla Foundation . Released on September 19, 2022, it serves as the final maintenance update for the Thunderbird 91.x branch. While newer versions like Thunderbird 115 "Supernova" and Thunderbird 128 are now available, version 91.13.1 remains relevant for organizations requiring a stable, long-term support (LTS) environment or for users with older hardware. Official Download Links Key Fixes in Version 91
: Fixed a high-impact vulnerability where sensitive information could leak when replying to HTML emails containing a META refresh tag.
To ensure security and authenticity, always use official sources for legacy software:
This release was primarily a security-focused update to bridge the gap for users who had not yet migrated to the next major release branch.