• https://support.google.com/a/answer/2466580
• https://dmarc.org/2015/08/receiving-dmarc-reports-outside-your-domain/
• https://powerdmarc.com/de/how-to-find-dkim-selector/
• https://mxtoolbox.com/DMARCRecordGenerator.aspx?
• https://easydmarc.com/tools/dkim-record-generator
• https://www.agari.com/blog/dkim-setup
• https://mxtoolbox.com/problem/dmarc/dmarc-external-validation?page=prob_dmarc
• https://dmarcadvisor.com/de/was-ist-external-destination-verification/
• https://www.sidn.nl/en/news-and-blogs/hands-on-implementing-spf-dkim-and-dmarc-in-postfix ← THIS IS GOLD!
• https://www.synology-forum.de/threads/strato-und-mail-server-einrichtung-dkim-spf-dmarc-workaround.92191/
• https://powerdmarc.com/how-to-read-dmarc-reports/
• https://www.mailercheck.com/articles/how-to-read-a-dmarc-report-and-actually-understand-it

Open Source DMARC-Report Analyzers/Visualizer:

• https://domainaware.github.io/parsedmarc/

#MX
dig -t MX +noall +answer netzwerkforensik.com
dig +noall +answer netzwerkforensik.com

netzwerkforensik.com.   150     IN      MX      5 smtpin.rzone.de.

smtpin.rzone.de.        1800    IN      A       81.169.145.97

# SPF
dig -t txt +noall +answer _spf.strato.com
dig -t txt +noall +answer netzwerkforensik.com

_spf.strato.com.        3600    IN      TXT     "v=spf1 ip4:81.169.146.128/25 ip4:85.215.255.0/24 ip6:2a01:238:20a:202::0/64 ip6:2a01:238:400::0/48 ip4:81.169.144.153 ip6:2a01:238:20a:202:50ff::153 -all"

netzwerkforensik.com.   150     IN      TXT     "v=spf1 include:_spf.strato.com mx -all"

#DKIM Selector 1
dig -t txt +noall +answer strato-dkim-0002._domainkey.netzwerkforensik.com

strato-dkim-0002._domainkey.netzwerkforensik.com. 150 IN TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAt3a1nbhQdD0MtbPT1r8DGZefoQlj3fSgtWdINsXsRl55OmOAf2QNR8B0SwC59dWqA+isuH/bQnU0f0OmO5A7p+cyfT9EekbWslP575NAnAYpsUJlBv/0O8qA6T/cLoDz6LsUYv000gFRqSSUe1BZnJ/sjg0f96UCkomT1aQRpSUSDwNYCqpQKQ/fWg9IS2fL+" "d2kR1rckqwoKdgbEtjr4i+ICn2SUodI1KkGusIivuBueMYfDh8RGYKvFv40UZlBSfuX71GkzEPvQPnQTfXLqM9F8q1kWq/mdWYy5R0KrWptAnuAmCZqujkgWmcqzLoTMln04oOxGFp/zkf8iA75lwIDAQAB"

#DKIM Selector 2
dig -t txt +noall +answer strato-dkim-0003._domainkey.netzwerkforensik.com

strato-dkim-0003._domainkey.netzwerkforensik.com. 150 IN TXT "v=DKIM1; k=ed25519; p=hB4fidO1tsRNeRkj6ySb9N2xwfNzERRFYLQhGQyQ9dE="

#DMARC
dig -t txt +noall +answer _dmarc.netzwerkforensik.com
dig -t txt +noall +answer netzwerkforensik.com._report._dmarc.wiretrip.de

_dmarc.netzwerkforensik.com. 150 IN     TXT     "v=DMARC1; p=quarantine; rua=mailto:dmarc-report@wiretrip.de; ruf=mailto:postmaster@wiretrip.de; sp=reject; fo=0:1:d:s; pct=100; aspf=s"

netzwerkforensik.com._report._dmarc.wiretrip.de. 43200 IN TXT "v=DMARC1;"

<?xml version="1.0" encoding="UTF-8" ?>
<feedback>
  <report_metadata>
    <org_name>google.com</org_name>
    <email>noreply-dmarc-support@google.com</email>
    <extra_contact_info>https://support.google.com/a/answer/2466580</extra_contact_info>
    <report_id>6934733341335759686</report_id>
    <date_range>
      <begin>1697673600</begin>
      <end>1697759999</end>
    </date_range>
  </report_metadata>
  <policy_published>
    <domain>netzwerkforensik.com</domain>
    <adkim>r</adkim>
    <aspf>s</aspf>
    <p>quarantine</p>
    <sp>reject</sp>
    <pct>100</pct>
    <np>reject</np>
  </policy_published>
  <record>
    <row>
      <source_ip>81.169.146.220</source_ip>
      <count>1</count>
      <policy_evaluated>
        <disposition>none</disposition>
        <dkim>pass</dkim>
        <spf>pass</spf>
      </policy_evaluated>
    </row>
    <identifiers>
      <header_from>netzwerkforensik.com</header_from>
    </identifiers>
    <auth_results>
      <dkim>
        <domain>netzwerkforensik.com</domain>
        <result>pass</result>
        <selector>strato-dkim-0002</selector>
      </dkim>
      <dkim>
        <domain>netzwerkforensik.com</domain>
        <result>fail</result>
        <selector></selector>
      </dkim>
      <spf>
        <domain>netzwerkforensik.com</domain>
        <result>pass</result>
      </spf>
    </auth_results>
  </record>
</feedback>

Der Fail in Zeile 43 kommt vermutlich vom zweiten Selector 0003 weil das kein RSA sondern ED25519 Zertifikat ist und google das noch nicht unterstützt. Sollte aber neutral bewertet werden - also Selector 1: pass und Selector 2: neutral.

• https://www.mail-tester.com/test-trw64bcwh

~~DISCUSSION~~