Older builds for legacy macOS versions (like High Sierra) can be found on MacUpdate . Why Users Downgrade Thunderbird
Navigate to the folder of your desired version (e.g., 102.15.1/ ), select your operating system (e.g., win64/ ), then choose your language (e.g., en-US/ ) to find the .exe or .dmg installer. thunderbird download previous versions
The Official Mozilla Thunderbird Archive contains every version released, dating back to 0.1. Older builds for legacy macOS versions (like High