stephenmwatts The target names in your CNAME records (ie, the
<sameuniquecode>.dkim.amazonses.com names) are DKIM selectors, not host names. As such, they don't resolve to any IP address and won't come up in a web browser, can't be pinged, etc.
I've checked the CNAMEs you've set up already and they're working as intended.
stephenmwatts Does this have to do with the fact that I can only create subdomains of the subdomain that you provide - <subdomain>.<companyname>.<domain>.com?
No not at all. For the free
username.opalstacked.com subdomains that we provide, the restriction is there because the
username.opalstacked.com portion of the subdomain is the one specific to your account. For other domains, ie your own domains that you've registered, you can set up your subdomains however you need them.