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Mozilla Thunderbird (en-US) · earlier release

Mozilla Thunderbird (en-US) 143.0.1

The URL Mozilla published for this release, and the SHA-256 of every file in it, so you can prove the copy you have is that one and not something else wearing the same name.

Released 23 September 2025.

This is not the current release

Mozilla Thunderbird (en-US) is now on version 154.0. An older build stops getting security fixes, so install one only when you have a reason: a plugin that broke, a machine that cannot run the new one, a bug you need to reproduce. If you just want Mozilla Thunderbird (en-US), take the current version.

Files in Mozilla Thunderbird (en-US) 143.0.1

Which one of these you want

This release shipped in more than one architecture, and the wrong one fails in a way that is not obvious: it either refuses to start or installs and then misbehaves. Take x64 unless the machine is genuinely 32-bit or ARM. Here is how to check which one your Windows is — and note that x86 means 32-bit, which is the part that catches people out.

The scope label says who the installer writes for. A user build installs into your own profile and needs no administrator rights; a machine build installs for everyone and does. On a work laptop where you cannot elevate, the user build is often the only one that will run at all. Silent install switches are on the same data.

Check the file you have

Windows does this without installing anything. In PowerShell:

Get-FileHash .\Thunderbird Setup 143.0.1.exe -Algorithm SHA256

Compare what it prints with the value above. If they match, your copy is byte-for-byte the one Mozilla published. If they do not, it is a different file, whatever it is called and wherever it came from. Paste a hash into the verifier and it will tell you which release it belongs to.

If PowerShell is blocked by policy on the machine, the same thing works from plain cmd with certutil -hashfile Thunderbird Setup 143.0.1.exe SHA256. On macOS or Linux it is shasum -a 256 Thunderbird Setup 143.0.1.exe.

If the link no longer works

Publishers retire old releases, and we do not host copies, so a link from an earlier version can stop working without notice. Two ways it fails: an honest 404, or — more confusing — the server answers normally but hands you the current downloads page instead of the file. If what arrives is a few kilobytes of HTML rather than an installer, that is what happened.

The hash on this page stays useful either way. It still identifies Mozilla Thunderbird (en-US) 143.0.1 wherever you find a copy, which is the whole point of publishing it: you can accept a file from somewhere else and still prove it is the one Mozilla built.

Releases either side of this one

Every Mozilla Thunderbird (en-US) release we index · where this data comes from