Postmark makes it very easy to authenticate your email messages with DKIM. If you have not already, log in to Postmark and create a sender signature or domain, then follow the steps to verify your domain.
If you are having trouble verifying your DKIM signature, there are two useful tools you can use to help fix them. Keep in mind that DNS changes might take several hours to propagate.
Checking DKIM Records
Using DKIM Core Key Check tool, insert the text before the
._domainkey as the Selector (it looks something like this:
20130425164621.pm) and then your Domain name. If DKIM is valid, it should show a result of “This is a valid DKIM key record”. If the record is not verified, go back to the instructions in Postmark and check the details to make sure your DNS records match.
Common DKIM Record Problems
Lookup DKIM Record in DNS
If you have added your DKIM record, waited 48 hours, and you still aren’t seeing that DKIM is verified, check to make sure you can see the record in your DNS using the
As an example, if your DKIM is valid, then it would be in DNS at
20130425164621.pm._domainkey.postmarkapp.com, you can check to see if it is there using this command:
$ dig 20130425164621.pm._domainkey.postmarkapp.com txt
dig command will return the DKIM record value seen in the authentication page. If it does not, it means the record is not in the correct location. Double check to ensure that you have added the record with the correct host/name in your DNS.
Duplicated Domain Name
Sometimes DNS providers will automatically add your root domain to the location, so it could have been added at
xxxxxxxxxxxxxx.pm._domainkey.domain.com.domain.com instead of the intended location. In that case, add the record with the host/name as
xxxxxxxxxxxxxx.pm._domainkey. instead of