Please provide more detail on what you are wanting to do. Details help. Thanks.

I was not able to configure the Mailserver for incoming mails correctly. A New Thunderbird installation has sollen this. Thank you for your attention!

You still haven't told us anything. Are you getting errors for the account? Can you provide screenprints of the setup that is failing?

I just did not receive mails, no error messages

Ok, I am confused. How do you know there is anything wrong?