Kleopatra, Version 2.0.9, Using KDE 4.3.1 (KDE 4.3.1) "release 6"
KMail, Version 1.12.2, Using KDE 4.3.1 (KDE 4.3.1) "release 6"
openSUSE 11.2

I cannot set a certificate to "trusted". I'm relatively new to
certificates and corresponding stuff, and probably I'm wrong in
some way.

Details:
I get and send Emails encrypted. But very often, Kmail warns me
about invalid certificate(s). Then, I click "Continue" and
"Forever" and I get or send my mails correctly. I'm really tired
to have to click the buttons so often.

Now I've seen in Kleopatra, that the provider's certificates are
not under "Trusted Certificates". The provider uses self-signed
certificates.

I've already spent hours to solve the problem myself, including
internet searches.

Any help to get the problem solved would be really appreciated.

Galatikum