Thunderbird 147.0 needs macOS 10.15 Catalina or later https://www.thunderbird.net/en-US/thunderbird/147.0/system-requirements/ Either your Mac allows upgrade to Catalina or a more recent macOS version or you have to download TB 115.9.0 from https://archive.mozilla.org/pub/thunderbird/releases/115.9.0/mac/ and install it on your Mac

I failed to install Thunderbird 147.0.dmg on my Mac operating under High Sierrra version 10.13.6. I am getting an error message that the file is damaged when I try to execute it.

The most current Thunderbird version you can run is the old Thunderbird 115.18.0esr

Thunderbird and Firefox versions from 116.0 to current requires macOS 10.15 (ten.fifteen) at minimum to run.

If you hardware allows you to update your macOS to 10.15 or later then you can use the current Thunderbird versions.

TB 115.9.0 from .. and install it on your Mac

Tb 115.8.0esr is not the most current Tb 115 ESR as Tb 115.18.0esr was the last version as you can see at https://www.thunderbird.net/en-US/thunderbird/releases/

https://archive.mozilla.org/pub/thunderbird/releases/115.18.0/mac/

Tb 115.8.0esr is not the most current Tb 115 ESR as Tb 115.18.0esr was the last version as you can see at https://www.thunderbird.net/en-US/thunderbird/releases/

Thank you, I missed that. The version numbers display on https://archive.mozilla.org/pub/thunderbird/releases/ is not in chronological order and I'd got lost in the big number of 115.x versions.....