DNS/SPF

DNS/SPF - SPF + DK + DKIM with Postfix

Beschreibung

SPF, DK und DKIM mit Postfix

• einrichtet
• testen

Wechsel auf Postfix

apt install postfix

SPF

DNS-Eintrag für SPF

v=spf1 +a +mx -all

SPF ist für diese Domain aktiviert

Eintrag optimieren

Wenn Sie mehrere Domains auf Ihrem Server hosten, sollten Sie ihn wahrscheinlich ebenfalls anpassen.

v=spf1 +a +mx +ip4:<ip.mail> ?all* <ip.mail>

Is the IP of the mail server that is responsible for sending the mails, it is automatically filled in when you apply the zones

After you do this modification you should apply it

Now let’s check with dig if the SPF is OK.

dig myserverplace.de TXT @ns1.myserverplace.de

You will see in the Answer section I have the following entry

myserverplace.de. 600 IN TXT "v=spf1 +a +mx +ip4:144.76.163.46 ?all"

So everything is ok, next onto DomainKeys

Postfix

Now let’s see what we need to do to configure Postfix to use OpenDKIM.

Execute the following command to see the milters configured

cat /etc/postfix/main.cf | grep "milters"
smtpd_milters = , inet:127.0.0.1:12768
non_smtpd_milters = , inet:127.0.0.1:12768

Open /etc/postfix/main.cf with your favorite editor, and add the following to the end of the file

# OpenDKIM
milter_default_action = accept
milter_protocol = 6
smtpd_milters = , inet:127.0.0.1:8891, inet:127.0.0.1:12768
non_smtpd_milters = $smtpd_milters

And your messages won’t be signed with DomainKey, only with DKIM

service postfix restart

Testing

There is an easy way to test if everything is correct, create an email account if you haven’t already and send a test mail to the following recepients, and the results are cut down because the text is too big* check-auth@verifier.port25.com

==========================================================
Summary of Results
==========================================================
SPF check: pass
DomainKeys check: pass
DKIM check: pass
Sender-ID check: pass
SpamAssassin check: ham* AAAA3QcKCQwA@appmaildev.com

============================================================
SPF result: Pass
============================================================
Domain: myserverplace.de
IP: 144.76.163.46

SPF Record: myserverplace.de
IN TXT = "v=spf1 +a +mx 144.76.163.46 ?all"

============================================================
DomainKey result: pass
============================================================
Signed by: admin@myserverplace.de

PublicKey: default._domainkey.myserverplace.de
IN TXT = "p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDAruBNqdsSCKBLwMrFNNKH8z0e7zmlAic7iRoJsDDJK3IlnW8j6G/T6a93m+jqYc6R38MBAZbeSv2LQJ0SepJEsr4Iqk41WFXPBKnyXReO1RXPW5/YnRe6dpJMEqsmPpl2TjInY7ve/6VCiVDOHn9RRrdB+x7CGeK2crgqSZVlFwIDAQAB;"

============================================================
DKIM result: pass
============================================================
Signed by: admin@myserverplace.de
Expected Body Hash: frcCV1k9oG9oKj3dpUqdJg1PxRT2RSN/XKdLCPjaYaY=
PublicKey: mail._domainkey.myserverplace.de
IN TXT = "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDMziMcgPTWK0kSUKxrgHHzEiWxNkZ2/M0Ugyr/8H9WtoCsJUM+Bc1C9VwqJ6yjTidecDrX7aL0lFZ9Mylku/wtSiPw6KLxMg2LG2vrMzlPTB2lmJNmg/EOu3KPC8BtAuOhXfwVH/ttQbzdKJKWqiCJn7jhF5oqEKnOCORxOQXKIwIDAQAB;"

Logs

You can check the following locations to see if there are errors

• /var/log/mail.err
• /var/log/mail.warn
• /var/log/mail.info
• /var/log/syslog

Note

Make sure you enable testing mode for DKIM if you plan to test, you can also cut down the EXPIRY time so the results propagate faster, so to enable testing mode set the key _domainkey to t=y; o=-

Anhang

Siehe auch

---

• DNS/SPF/Test