If your emails are going to spam despite having a clean list and a warmed-up domain, the problem might be your authentication records. SPF, DKIM, and DMARC are the three pillars of email authentication — and without all three in place, inbox providers have no way to verify that your emails are legitimate.

What Is SPF?

SPF (Sender Policy Framework) is a DNS record that tells receiving mail servers which IP addresses are authorized to send email on behalf of your domain.

Without SPF, anyone can send email pretending to be from your domain. With SPF, receiving servers can check: “Is this email coming from an IP that mailpipe.co said is allowed?” If not, the email fails SPF and is more likely to be marked as spam or rejected.

Example SPF record:

v=spf1 include:mailpipe.co ~all

The ~all means “emails from unauthorized IPs should be treated as suspicious but not rejected.” For stricter enforcement, use -all.

What Is DKIM?

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to your emails that receiving servers can verify using a public key published in your DNS records.

When you send an email, MailPipe signs it with a private key. The receiving server looks up your public DKIM key in DNS and verifies that the signature matches. If it does, the email hasn’t been tampered with in transit — and it genuinely came from your domain.

DKIM is especially important because it survives email forwarding (unlike SPF, which can break when email is forwarded).

What Is DMARC?

DMARC (Domain-based Message Authentication, Reporting, and Conformance) ties SPF and DKIM together and tells receiving servers what to do when an email fails authentication.

Example DMARC record:

v=DMARC1; p=quarantine; rua=mailto:dmarc@mailpipe.co

DMARC policies:

  • p=none — Monitor mode. Collect reports but take no action on failures.
  • p=quarantine — Send failing emails to spam.
  • p=reject — Reject failing emails outright. The strongest protection.

DMARC also provides reporting — you’ll receive aggregate reports showing which sources are sending email on behalf of your domain, helping you detect spoofing and misconfigured sending services.

Why All Three Are Required

Gmail’s bulk sender guidelines (updated in 2024) now require SPF, DKIM, and DMARC for all senders sending more than 5,000 messages/day to Gmail addresses. Yahoo has similar requirements. Without all three:

  • Your emails are more likely to land in spam
  • Your domain can be spoofed by phishers
  • You have no insight into who is sending email on your behalf
  • Domain warmup is significantly less effective

How to Check Your Authentication Records

You can verify your current SPF, DKIM, and DMARC records using free tools like MXToolbox or Google’s Admin Toolbox. Look for:

  • SPF record present and includes your sending domain/IP
  • DKIM selector published in DNS
  • DMARC policy set to at least p=none with a reporting address

MailPipe Validates Authentication Automatically

When you connect your domain to MailPipe, we check your SPF, DKIM, and DMARC configuration automatically. If anything is missing or misconfigured, we flag it before you send a single email — protecting your reputation from the start.

Need help setting up proper email authentication? Create your free MailPipe account and we’ll walk you through the setup step by step.