Question Enable DKIM on all Domains

[UweP]

Hi. How can I enable DKIM automatically on all domains. Or does that matter, if umm, a domains DNS server is not yet set to my server, and a dkim is present in the dns zone of the domain on my server? it should just not be used right?

 

[UweP]

Oh and, is this correct:

Received-SPF: pass (google.com: domain of my@mail.tld designates 2a01:4f8:110:12a1::2 as permitted sender) client-ip=2a01:4f8:110:12a1::2;
Authentication-Results: mx.google.com;
dkim=temperror (no key for signature) header.i=@mydomain.tld;
spf=pass (google.com: domain of my@mail.tld designates 2a01:4f8:110:12a1::2 as permitted sender) smtp.mailfrom=my@mail.tld;
dmarc=pass (p=NONE dis=NONE) header.from=mydomain.tld
Received: from [192.168.2.107] (myhost.isp [my.isp.ip])
by baby.freakyonline.de (Postfix) with ESMTPSA id 3A35147E0081
for <mymail@gmail.com>; Mon, 21 Nov 2016 18:38:48 +0100 (CET)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mydomain.tld;
s=default; t=1479749928;
bh=somethignencryptedorhwat; l=8;
h=To:From:Subject;
b=somekeydunnoifishouldpost
To: mymail@gmail.com

because it says temperror but later shows a dkimg signature
oh it's missing the key - why is that? I've set up plesk to use dkim for mail for that domain?