Hello there '''''Having the download''''' You can download the version of Thunderbird 115.0 . To have security updates for this version is only for the firefox version of this version number and is valid till august of 2026.If you download that version number for Thunderbird version 115.x Esr on a unsupported Window operation system like Win 7 it s possible to do , but there s no security update anymore for this version. https://www.thunderbird.net/en-US/thunderbird/releases/ '''''Using an outdated version''''' https://archive.mozilla.org/pub/thunderbird/releases/ You should pick the right version out of this Thunderbird release list. And use the 115.0 versions for that wish. But these versions are unsupported. '''''The best option''''' Changing the Windows operating system and the Thunderbird version Both to the latest version s for 2026. https://www.thunderbird.net/en-US/thunderbird/all/