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Domain Authentication

To send emails reliably and securely from MX18, authenticating your domain is a critical step. This ensures mailbox providers like Gmail, Yahoo, and Outlook trust your email and deliver it to inbox — not spam folders.

What is domain identity and why authenticate It?

Domain Identity is a way to prove that you own the domain you're sending emails from. Without authentication, mailbox providers may treat your email as suspicious or spoofed.

Authenticating your domain improves:

  • Inbox placement (less chance of being flagged as spam)
  • Brand visibility (with DMARC alignment)
  • Compliance with ISP sender guidelines (like Google/Yahoo requirements)

How MX18 domain authentication works

MX18 helps you verify your domain using three industry-standard DNS records:

SPF (Sender Policy Framework)

Authorizes MX18 IPs to send on behalf of your domain.

Example: 

v=spf1 include:spf.mx18.io ~all

DKIM (DomainKeys Identified Mail)

Digitally signs your emails using a unique key pair, protecting them from tampering.

Example: 

v=DKIM1; k=rsa; p=MIIBIjANBg...

DMARC (Domain-based Message Authentication, Reporting & Conformance)

Tells ISPs how to handle unauthenticated messages from your domain.

Example: 

v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

Update DNS records with your registrar

To complete domain authentication, add the provided SPF, DKIM, and DMARC records in your domain DNS settings.

Here are guides for popular registrars:

Not sure where your domain is registered? Use whois tool to find out.

Verifying DNS propagation

After you've added the records:

  1. Go to your MX18 Dashboard > Sender Authentication

  2. Click the Verify button next to your domain

  3. MX18 checks your DNS for the expected SPF, DKIM, and DMARC records

If successful, your domain will be marked as Verified and ready for sending.

DNS propagation may take up to 48 hours depending on your registrar and TTL settings.

Need help?

  • Double-check for typos or extra whitespace in DNS values

  • Ensure you're adding records in the correct format (TXT/CNAME)

  • For assistance, reach out to support@mx18.com