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.


Got this question answered by SendGrid's support team. Pasting their response here:

If I recall, 1 & 1 doesn't support the _ value in the CNAME record.

What you can do is create a TXT record instead.

Head over to your SendGrid account -> Select Settings -> Whitelabel.

Delete your old whitelabel and add a new one using the same subdomain and domain ' mail.'. This time, Turn off the automated security box so we use TXT records vs. CNAME records for your DKIM config.

Back on 1and1.com's configuration screen I was able to create the TXT records as spec'd by SendGrid.

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  • I have tried this solution and it looks that now for TXT they generate a subdomain like this: m1._domainkey.... so they are using underscore here too. Maybe they changed since your answer. – Daniel Dudas Feb 8 '17 at 18:24

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.

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