I used mail-tester.com to check my deliverability. It gave me a score of just 1.5 out of 10. It complained about an invalid DKIM signature and lack of MX record. I'm not clear on how to update the DKIM signature and when I tried to add a DNS MX record as it suggested, the zone editor said "ckespa.(my domain) already has a CNAME record" Any ideas on how to fix these problems?