As in quite a few threads explained the trailing dot is by no means necessary. In your case I’d assume the actual issue will be that that CNAME record is proxied. Make sure it is .
So a couple of things to note that I should have included originally:
I have a working DKIM record for “domain.com” That is currently set to google apps domain and it is a TXT record. I am trying to set up a subdomain, “test.domain.com” on an Apple iCloud+ and it uses the CNAME approach above. I don’t know if I need to modify the initial DKIM record to allow the subdomain? Maybe that is the issue?
This is my first time setting up a separate email subdomain.