Hi,
I tried to use kmail with kleopatra to encrypt and sign email with
SMIME. For that I exported my working certifikates from Thunderbird
as *.p12 file.

This file Kleopatra imports whitout any error, including the CA-Cert.
But I cannot use it, because any usage (e.g. change Passphrase, signing
email in kmail) that requests the input of the passphrase with pinentry
fails - with the error: "wrong password" - whatever I put in during the
import.

I can import Certs of other users in kleopatra, and signed mails from
others are show correct as signed from <sender>.
encryption is possible too.

see the gnupg log below.