Follow these steps to create a CNAME record. This will help tinyAlbert authenticate your custom domain.
Verifying your domain
Log in to your Shopify Admin account.
Go to Settings and select Domains.
Click the domain for which you need to add a CNAME record. Click Domain settings and then select Edit DNS settings.
Click Add Custom record and then select the record type as CNAME record.
Specify the Host Name = tec1._domainkey
Specify Points to = tec1.dkim.tinyemail.com
Click Confirm.
Verify your DKIM Set up - Authenticate Your Sending Domain Using DKIM
Feel free to contact us at [email protected] for any help.