I was never able to get ProSeries 2022 to work with Thunderbird or my MAPI-compliant email client.  During my 6 hours on the phone with Intuit tech support, they tried lots of things, eventually helping me to uninstall Thunderbird and install Microsoft Outlook 365 64-bit.  I can now email through both ProSeries 2021 and ProSeries 2022.  Thank you, Chris!!!  I hope this thread is helpful to other tax preparers.