You can find but may not want it yet.
https://www.ghacks.net/2018/08/07/how-to-migrate-32-bit-thunderbird-to-64-bit-on-windows/

Thunderbird 32 did work fine in win10 64.


On 3/19/2020 10:45 AM, Mark Bannister wrote:
> I didn't even know they had a 64 bit yet.
> 
> On 3/19/2020 11:14 AM, Jim Short wrote:
>> We are going back to Thunderbird 32 bit.
>> Thanks Mark
>>
>> On 3/19/2020 7:59 AM, Mark Bannister wrote:
>>> Just tested with Win 10 64 , Pdox 11, thunderbird 68.6.0 32 bit and it
>>> worked fine.
>>> Thunderbird was open and set as the default email client.
>>>
>>> On 3/19/2020 8:34 AM, Jim Short wrote:
>>>> P9
>>>>
>>>> Win 10 64 not creating mail, says no mail client use Outlook.
>>>>
>>>> Win 10 32 launches Thunderbird correctly
>>>>
>>>> Jim
>>>>
>>>> m.addAddress(addr)
>>>> m.setSubject(subj)
>>>> m.setMessage(body)
>>>> m.sendDlg()
>>>> m.emptyAddresses()
>>>>
>>>> Any ideas?
>>>
>