Question DKIM Fails

[voelu28]

Hello,
I have a question. I get this every day:

<feedback>
<report_metadata>
<org_name>Yahoo! Inc.</org_name>
<email>[email protected]</email>
<report_id>XXXX</report_id>
<date_range>
<begin>XXXXXX</begin>
<end>XXXXXX</end>
</date_range>
</report_metadata>
<policy_published>
<domain>domain.de</domain>
<adkim>r</adkim>
<aspf>r</aspf>
<p>quarantine</p>
<pct>5</pct>
</policy_published>
<record>
<row>
<source_ip>XXXXXX</source_ip>
<count>1</count>
<policy_evaluated>
<disposition>none</disposition>
<dkim>fail</dkim>
<spf>pass</spf>
</policy_evaluated>
</row>
<identifiers>
<header_from>domain.de</header_from>
</identifiers>
<auth_results>
<spf>
<domain>host.domain.de</domain>
<result>pass</result>
</spf>
</auth_results>
</record>
</feedback>

MXToolbox says that in my external DNS Records is everything fine. I checked DKIM, DMARC and SPF.
I think its a problem with the host. Because a subdomain (host.domain.de) is my hostname?

 

[voelu28]

Pls help