You can add a CAA record to your zone file at Gandi, if you are using our DNS.
In this case, from the zone file edition page, choose a new version and then on the right, select the “expert mode” for editing your zone.
The standard syntax for SSL certificates purchased from Gandi will be like the following:
@ IN CAA 0 issue "comodoca.com"
After you have saved your version of the zone, remember to activate it for it to take effect.
@ IN CAA 0 issue "comodoca.com" @ IN CAA 0 issue "letsencrypt.org"