I tried creating domain keys and spf for our campaign but have a query with regards to the key.
It shows as:
TXT Name: cm._domainkey.mydomain.com
but RFC 1035 says that underscores are not valid and it should use a hyphen instead.
Can anyone advise?
You likely have already sorted this out, but the RFC forbids the use of underscores in A and MX records only. No problem for a TXT record.