Add a DKIM key for a subdomain

Protect against spoofing & phishing, and help prevent messages from being marked as spam

Your organization might use subdomains for certain business purposes. For example, if your domain is solarmora.com, you might send email from a subdomain called mail.solarmora.com. Or, you can use a subdomain for tech support information, for example support.solarmora.com.

Some domain providers let you add a DKIM TXT record directly to the subdomain, using the same steps in Turn on DKIM for your domain.

If your domain provider doesn't let you add TXT records to a subdomain, add a modified TXT record to the parent domain. This enables DKIM for the subdomain.

Step 1: Get the DKIM TXT record name and key value for the parent domain

To get the TXT record name and DKIM key value, follow the steps in Generate a DKIM key for your domain.

Important: The subdomain must be for the domain you select in your Admin console, in the Selected domain menu on the Email authentication page.

Step 2: Modify the TXT record name

Modify the TXT record name from the Admin console, so it can be used for a subdomain. To modify the TXT record name, add a period (.) followed by the subdomain name to the end of the TXT record name.

For example, if your subdomain is mail.solarmora.com:

Change the default TXT record name from google._domainkey to google._domainkey.mail

In this example, your subdomain is support.solarmora.com:

Change the default TXT record name from google._domainkey to google._domainkey.support

Step 3: Add the modified TXT record & DKIM key to the parent domain

Log into your domain provider and add the DKIM information from Steps 1 and 2:

Keep these tips in mind:

  • TXT record limits: Some domain providers limit TXT record length. If yours does, read TXT record limits and DKIM keys.
  • DKIM can take up to 48 hours to start: After adding a DKIM key, it can take up to 48 hours for DKIM authentication to start working.
  • Multiple domains: If you’re setting up DKIM for more than one domain, complete the steps below for each domain. You must get a unique DKIM key from the Admin console for each domain.

For help with your domain sign-in information, settings, or TXT records, contact your domain provider. For example, if Google Domains is your domain provider, get help here. Google doesn't provide technical support for third-party domain providers.

  1. Sign in to the management console for your domain provider.
  2. Locate the page where you update DNS records for your domain.
  3. Add a TXT record for DKIM:
    • In the first field, enter the modified TXT record name.
    • In the second field, enter the TXT record value (DKIM key) from your Admin console. 
  4. Save your changes.
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