In the SendGrid dashboard, navigate to Settings > Sender Authentication > Authenticate Your Domain; enter your domain name and choose whether to use Automated Security (recommended).
With Automated Security enabled, SendGrid generates three CNAME records: two DKIM records (by default at s1._domainkey.yourdomain.com and s2._domainkey.yourdomain.com) and one SPF branding record (at a subdomain like em.yourdomain.com); copy these exactly as shown.
Add all three CNAME records to your DNS provider; CNAMEs cannot coexist with other record types at the same name—if you already have a TXT at s1._domainkey, delete it first.
Return to the SendGrid dashboard and click Verify; DNS propagation can take up to 48 hours. The UI shows a green check when each record resolves correctly.
Once verified, SendGrid automatically manages DKIM key rotation on your behalf via the CNAME delegation; you do not need to manually rotate keys.
If your domain already has an SPF TXT record at the apex, you do not need to add SendGrid's IP ranges manually—the CNAME-based branding record covers SPF alignment for the subdomain envelope sender SendGrid uses.
Known gotchas
If you use a custom DKIM selector (available in SendGrid's settings), the generated records change to a1._domainkey and a12._domainkey; use custom selectors when you need multiple SendGrid accounts for the same domain to avoid DNS conflicts.
CNAME-based authentication means SendGrid controls the resolved key; if you need full ownership of your DKIM keys for compliance reasons, use BYODKIM (bring your own DKIM) instead of Automated Security.
Authenticating a domain in SendGrid does not automatically publish a DMARC record; you must add _dmarc.yourdomain.com separately—SendGrid authentication alone does not protect against spoofing of your From domain.
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp