How can I check if my DKIM and SPF records are valid?
If you are having trouble verifying your SPF or DKIM records there are two useful tools you can use. Keep in mind that DNS make take several hours to propagate.
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. If DKIM is valid, it should show a result of This is a valid DKIM key record. If the record is not valid, go back to the instructions in Postmark and check the details to make sure your DNS records match.
Using SPF Record Testing tool, just insert your domain and click Get SPF Record. For Postmarkapp.com, it would show a result like this:
<code>Checking to see if there is a valid SPF record. Found v=spf1 record for postmarkapp.com: v=spf1 a mx include:spf.mtasv.net include:_spf.google.com include:cmail1.com ~all
The important part to notice above is include:spf.mtasv.net which tells ISPs that Postmark can send on behalf of your domain.