Unable to sign e-mails with Thunderbird 78.3.2 and Nitrokey Start in Windows 10

Nitrokeys
3
  1. Have you imported the public key?

That was it!

First of all I wanted to test the simplest case Signing, where only the secret key is needed. But obviously Thunderbird expects the public key in his keyring in this case too.

When I imported the public key, it worked.

Thank you!