I'm struggling to configure white labeling between sendgrid and 1and1.com.
Sendgrid asks me to create a variety of subdomains on my domain registrar with specific CNAME values. I'm able to create most of them but I was stuck on:
1and1.com is giving me an "invalid subdomain error. The subdomain could not be created. An error has occurred" Anyone else come across this and resolved it? Do I need to switch registrars?
I can create the subdomain without the underscore but then it doesn't validate against sendgrid.