To authorize Postmark to send emails on your behalf and achieve SPF alignment you will have to configure a CNAME record as per the instructions found in the article below.

Postmark also support DKIM and can be configured to DKIM sign your emails for further resilience and failover if SPF fails. For instructions on how to set up DKIM signing for your Postmark email please click on the button below.

Create a free OnDMARC account to test your configuration.