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:
s1._domainkey.<mydomain>
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.
Got this question answered by SendGrid's support team. Pasting their response here:
Back on 1and1.com's configuration screen I was able to create the TXT records as spec'd by SendGrid.
1&1 does not allow underscores in their DNS Records, or at least in their CNAME DNS Records, despite underscores being allow in the RFC. I can't find documentation from them on it, but it's a problem I've heard of many times in the past; you might want to contact their support to confirm.