Guides & Docs

Correct DNS Setup — The Foundation of Email Deliverability

By
Matt Hayes
July 2, 2025
Blog

If email deliverability is a house, DNS is the foundation.Without it, everything else—warm-up, content, engagement—crumbles.You could have the best content, a fully warmed IP, and squeaky-clean data, but if your DNS isn’t configured correctly, your emails will never reliably reach the inbox. Worse, they might not get delivered at all.Think of DNS as your passport to the inbox. Without SPF, DKIM, DMARC, and reverse DNS, you’re an unverified stranger knocking on your subscribers’ doors.

If email deliverability is a house, DNS is the foundation.

Without it, everything else—warm-up, content, engagement—crumbles.

You could have the best content, a fully warmed IP, and squeaky-clean data, but if your DNS isn’t configured correctly, your emails will never reliably reach the inbox. Worse, they might not get delivered at all.

Think of DNS as your passport to the inbox. Without SPF, DKIM, DMARC, and reverse DNS, you’re an unverified stranger knocking on your subscribers’ doors.

What You Need to Know (and Actually Do):

🔹 SPF (Sender Policy Framework)

SPF tells inbox providers which IP addresses and servers are allowed to send emails on your behalf.

If your SPF is missing or misconfigured:

  • Emails may fail authentication checks.
  • You risk higher spam folder placement or outright rejections.
  • Spoofers can impersonate your domain more easily.

How to set up:

  • Create a TXT record in your DNS with your sending services included.
  • Use tools like MXToolbox SPF Checker to validate your SPF record.
  • Remember: SPF has a lookup limit (10), so avoid bloated records.

🔹 DKIM (DomainKeys Identified Mail)

DKIM attaches a digital signature to each outgoing email using a private key. Receiving servers use the public key published in your DNS to verify it.

Without DKIM:

  • Inbox providers see your emails as less trustworthy.
  • Your messages may get tampered with without detection.
  • You lose a key authentication signal for deliverability.

How to set up:

  • Most ESPs (like SendGrid, Mailgun, or your ESP) will provide DKIM keys.
  • Publish the provided public key as a TXT record in your DNS.
  • Validate using your ESP or tools like dmarcian’s DKIM Inspector.

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

DMARC builds on SPF and DKIM, telling inbox providers what to do when authentication fails and providing visibility via reports.

Why DMARC matters:

  • Helps prevent spoofing and phishing from your domain.
  • Gives you actionable insights into who’s sending using your domain.
  • Enhances inbox trust.

How to set up:

  • Start with p=none (monitor mode) while reviewing reports.
  • Gradually move to p=quarantine or p=reject once you’re confident.
  • Use our DMARC Guide to set up correctly.

🔹 Reverse DNS (PTR Records)

Reverse DNS links your sending IP back to your domain, helping providers confirm your identity.

Without PTR:

  • Microsoft, in particular, may refuse or junk your emails.
  • Some ISPs will see your IP as suspicious.

How to set up:

  • PTR records are configured at your hosting provider or with your ESP.
  • Ensure your sending IP resolves to your sending domain (e.g., mail.yourdomain.com).

🔹 Bonus Deliverability Enhancers

  • Google Postmaster Tools: Free insights into your domain’s performance with Gmail (spam rate, IP reputation, and more).
  • Microsoft SNDS: Helps monitor your IP’s reputation with Microsoft.
  • BIMI (Brand Indicators for Message Identification): Display your logo in inboxes that support BIMI, adding trust and increasing open rates.

Common Mistakes to Avoid:

🚫 Publishing incomplete SPF records.

🚫 Not rotating or checking DKIM keys after ESP changes.

🚫 Setting DMARC to reject immediately without monitoring.

🚫 Overlooking PTR records when changing IPs.

🚫 Thinking it’s “set and forget”—DNS should be audited quarterly.

Recommended Tools:

MXToolbox — DNS and blacklisting checks

Google Postmaster Tools — Gmail insights

BIMI Group — BIMI setup resources

✅ Mailyser Postmark DMARC Guide

Why It Matters for Your Business:

Your sender reputation is built on trust, and DNS is the first handshake between you and inbox providers. Without proper DNS:

❌ Your emails might land in spam.

❌ Your warm-up efforts will be wasted.

❌ Your subscribers may never see your carefully crafted campaigns.

With correct DNS:

✅ You maximize your chances of inbox placement.

✅ You protect your domain from spoofing and phishing.

✅ You build a solid foundation for your email program.

Takeaway:

Correct DNS setup is like showing your ID before entering the inbox party.

🚪 No SPF, no DKIM, no DMARC, no entry.

✅ Get your DNS right, and you open the door to consistent inbox placement, brand trust, and higher deliverability.

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