This article covers the SPF and DKIM authentication processes for Postmark and how they are managed in Valimail. While only one of the two authentication methods is required for an email to pass DMARC, our recommendation is to configure both whenever possible.

1. Navigate to your Sender Signatures tab in your Postmark account.

2. Under the domain you are adding DKIM authentication for, click DNS Settings or Add a DKIM DNS record.

3. A DKIM record will be shown that needs to be added to your DNS as a TXT record.

4. The Postmark TXT DKIM key record needs to be published in Valimail Enforce.

5. Once the record is added Valimail Enforce, DKIM will show as verified in your Postmark account. You can use the Verify button to initiate a manual verification check if you do not see the record automatically become verified.

6. After the DKIM record is verified, we will begin signing emails sent through Postmark using this domain with DKIM.

You can find the instruction on how to set up DKIM in Postmark here.

You can find more detailed information on how to add a DKIM key in Valimail, here:

Once you establish that Postmark is an authorized sender for your domain, you will need to add the service in your Enabled Senders.

You will find more detailed information on how to add a service for your domain in Valimail, here:

Note: We encourage you to use the comment section for any useful information about your sending service, such as the name of the service owner, change request ticket numbers, etc.

You may notice that Postmark emails are not authenticated via SPF, even after you have added Postmark to your domain's configuration. This is likely caused by Postmark not sending SPF aligned-mail and can be corrected by configuring a CNAME record.

More details on how to achieve that are found in the article here.