amavis-dkim: How to discard mail with no or invalid signature

[Gerhard Rappenecker]

Hi all,

I'd like to discard, reject or quarantine mails from a specific domain, but only if they have no or no valid DKIM signature.

I suspect that's a trivial task but I'm a beginner working with postfix/amavis and cannot find any helpful documentation about this.

My environment:
postfix 2.11.6
amavisd-new-2.8.1
amavisd.conf:
  $enable_dkim_verification = 1
  $enable_dkim_signing = 1;

DKIM signing and verification work fine, but the mail is beeing delivered independent of the DKIM authentication-result

Can anyone help me?

Regards
Gerhard