If you are already a current user of SendGrid or have records added for Sendgrid due to another service, you'll need to follow these steps below in order to link your domain. In short, you will need to add a third level domain to differentiate between your existing records and the record for Promoter.
Suppose your domain is pearcomputers.com...
1. Visit your DNS and add a subdomain to your account. You can name this whatever you'd like in your DNS. In the example below, we used the namesurvey.
The survey portion of the domain is what helps us for the CNAME dkim1 and dkim2 records that will need to be added.
2. Visit your Deliverability Settings in Promoter and proceed with the rest of the steps by entering in your subdomain and click 'Add'. With the subdomain example, SendGrid would generate the following CNAME dkim and mail_name records: