DNS Certification Authority Authorization (CAA) uses your DNS records to let you specify which certificate authorities are allowed to issue certificates for the domains you own.
✔ All looks good
0 iodef "mailto:firstname.lastname@example.org"
0 issuewild ";"
0 issue "letsencrypt.org"
If you're not quite ready to test your DNS CAA record yet, then perhaps worth a visit to: