DomainKeys Identified Mail (DKIM) is an email authentication method that guarantees the authenticity of the message by using a private key to digitally ‘sign’ the message. The email receiver can check if this signature is valid, authenticating the identity of the sender.

To ensure that emails sent from your FastMail domain have DKIM signatures, you'll need to create CNAME records for your domain. In order to do this, you will need to create entries for the following three CNAME records provided by FastMail.

Setting Up DKIM for FastMail 

FastMail requires you to publish 3 different DNS CNAME records in order to enable DKIM signing for your domains on FastMail. They are as follows: 

After publishing the records in your domain’s DNS, and saving changes, you need to wait for 24-48 hours for your DNS to properly process the changes. When done, check the validity of your DKIM record using our DKIM record lookup tool to ensure that your record is error-free. 

Sign up with your free DMARC analyzer to set up DMARC for your domain.