Email Deliverability
How Failed SPF and DKIM Break Your Cold Outreach (And How to Fix It Fast)
May 8, 2025
SPF and DKIM are essential for cold email success. When either fails—due to missing, misconfigured, or unauthorized records—your emails may be silently discarded, land in spam, or get blocked entirely. This article walks you through what SPF and DKIM actually are, what it means when they fail, and exactly how to fix them so your outreach hits the inbox, not the junk folder.
Why SPF and DKIM Failures Stop You From Inboxing
Imagine your email is a traveler at a border checkpoint:
SPF is your return address — it shows whether you're allowed to send from your claimed location.
DKIM is your signature — it proves the message hasn't been tampered with.
DMARC is the border agent — they decide whether to let you through based on the results of SPF and DKIM.
If SPF or DKIM fail, mailbox providers lose trust in your email. That trust is what gets you into the inbox. Without it? You’re spammed, filtered, or flat-out blocked.
Breaking Down SPF and DKIM Failures (Plain English)
What is SPF?
SPF (Sender Policy Framework) checks whether the IP address sending your email is allowed to do so. This check looks at the domain’s DNS record.
✅ SPF Pass: The sending server IP is listed in the domain’s SPF record.
❌ SPF Fail: The server’s IP is not listed. This happens when your tool or platform isn’t added to your SPF record.
Example: You use outreach@yourbrand.com to send cold emails through a third-party platform, but that tool’s IP address isn’t added to your SPF DNS record. SPF fails, and mailbox filters get suspicious.
What is DKIM?
DKIM (DomainKeys Identified Mail) verifies that the message was not altered after being sent. It uses a cryptographic signature that gets validated by the receiving server.
✅ DKIM Pass: The signature matches the public key stored in your domain’s DNS.
❌ DKIM Fail: The signature is missing, broken, or not connected to your domain.
📬 Example: You set up a tool to send email, but forget to publish the DKIM record in your DNS. Or the tool signs emails using their domain, not yours. Result? DKIM fails, and you look like a spammer.
What is DMARC?
DMARC (Domain-based Message Authentication, Reporting & Conformance) ties SPF and DKIM together. It tells mailbox providers how to handle a message when SPF or DKIM fails.
DMARC will only pass if either SPF or DKIM passes and is connected to your domain.
🚨 If both SPF and DKIM fail, DMARC fails too. Your email is now untrusted—and inboxing becomes near impossible.
Why These Failures Happen (and What Causes Them)
How to Fix SPF and DKIM Failures (No Guessing)
1. Fix SPF
Log in to your domain registrar or DNS provider.
Create or update your SPF record to include your platform’s sending IP/domain.
Sample SPF record:
This record acts like a whitelist. If an email comes from a server not included in this record, SPF will fail.
Only include services you actively use — don’t overload with includes.
2. Fix DKIM
Ask your platform or email tool to generate a DKIM key pair.
Publish the public key in your domain’s DNS under the correct selector.
Example DKIM DNS entry:
This record helps mailbox providers verify that your email was truly sent by you and wasn’t tampered with in transit.
Ensure emails are signed using your domain and selector.
3. Test Your Setup Before Sending
Use inbox testing tools or send to test accounts to verify:
✅ SPF: Pass
✅ DKIM: Pass
✅ DMARC: Pass
Why This Isn’t Just “IT Stuff” — It’s Revenue
Want to Avoid These Mistakes Altogether?
Book a demo with our team — we’ll help you break down your DNS, show what’s working (or not), and make sure your next cold campaign lands inbox-first.
No fluff. Just smarter sending.
