I should re-iterate I download the emails to use in an offline client. Their service doesn’t support third party clients to receive and send email.
When I do taxes, I need to search thousands of emails for receipts and the tuta apps make this impossible. This is my workaround.
My bad. Its been a while, but Thunderbird at one point. If I remember right there was an update relatively recently that made it much more difficult to import offline emails, so if you find a better alternative let me know.