DKIM

DomainKeys Identified Mail

Links

DKIM checks

DKIMvalidator

• dkim check
• http://www.myiptest.com/staticpages/index.php/DomainKeys-DKIM-SPF-Validator-test

DKIM documentation

• DKIM and postfix
• Postfix and dkim-milter
• DKIM with CNAME or TXT
• About DKIM
• DKIM with Sendmail
• https://wiki.debian.org/OpenDKIM
• SPF and DKIM on Debian
• OpenDKIM

• dkim key rotation

DKIM tags

• https://mxtoolbox.com/dmarc/dkim/dkim-signature-tags

HOWTO

Find published dkim key

In mailheader look for 'd=' and 's=' to get domain and selector, then

dig <selector>._domainkey.<domain> TXT

Check if keys match

dig myselector._domainkey.example.com txt

and save the bit from "p=" to public.key.b64 You will probably need to remove the quotes/spaces:

| sed 's/[\" \"|\"$]//g' 

openssl enc -base64 -d -in public.key.b64 -out public.key
openssl rsa -pubin -inform DER -in public.key -noout -modulus

and compare the shown modulus with

openssl rsa -in private.key -noout -modulus

They should be identical