- You created a CAA record
- You're trying to add an Certificate Authority Authorization to it
- You're using the IODEF tag
- You get error “Must be a URL or an email” when adding an email value
- Primary DNS
- Your value format does not match the RFC6844 requirement
CAA 0 iodef "mailto:firstname.lastname@example.org"
- You must add the prefix "mailto:" before the email