Introduction
Email authentication is essential if you want to protect your domain from spoofing, improve inbox placement, and build trust with your audience. But many domain owners, marketers, and IT teams make small mistakes that have big consequences — like emails going to spam or being rejected entirely.
In this article, we’ll explore the 10 most common email authentication mistakes and show you how to fix them to improve your email security and deliverability.
1. Not Having SPF, DKIM, or DMARC Set Up
The mistake: Sending emails without any authentication.
Why it’s bad: Emails are more likely to be marked as spam or spoofed. Some inboxes may reject them completely.
How to fix it: Set up SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication Reporting and Conformance).
2. Having Multiple SPF Records
The mistake: Creating more than one SPF TXT record in DNS.
Why it’s bad: Causes SPF validation failures — even for legitimate emails.
How to fix it: Merge all mechanisms into a single SPF record, for example:
v=spf1 include:_spf.google.com include:sendgrid.net ~all
3. Using “+all” in SPF Records
The mistake: Ending your SPF record with +all.
Why it’s bad: Authorizes any server to send emails — making your domain vulnerable to abuse.
How to fix it: Use ~all (soft fail) or -all (hard fail) instead.
4. Not Aligning SPF or DKIM with the “From” Domain
The mistake: Authentication passes but doesn’t match the visible From address.
Why it’s bad: DMARC will fail due to domain misalignment.
How to fix it: Ensure SPF (Return-Path) and DKIM (d=domain) match or align with the “From” domain.
5. Missing DKIM Signatures
The mistake: Sending emails without DKIM.
Why it’s bad: Reduces trust and fails DMARC alignment if SPF fails.
How to fix it: Enable DKIM in your sending service and publish the key in your DNS.
6. Misconfigured DMARC Policies
The mistake: Using p=none forever or setting p=reject without testing.
Why it’s bad: Doesn’t protect your domain (in case of none) or may block legit emails (in case of reject too early).
How to fix it: Gradually move from p=none → p=quarantine → p=reject after reviewing DMARC reports.
7. Ignoring DMARC Reports
The mistake: Not reviewing DMARC RUA reports sent to your email.
Why it’s bad: You miss spoofing attempts or misconfigurations.
How to fix it: Use tools like:
8. Exceeding SPF DNS Lookup Limits
The mistake: Using too many include: mechanisms, resulting in more than 10 DNS lookups.
Why it’s bad: SPF check fails silently even if syntax is valid.
How to fix it: Use SPF flattening tools and minimize includes:
9. Forgetting to Update DNS When Adding New Senders
The mistake: Adding services like Brevo, Mailgun, or Zoho but not updating SPF/DKIM records.
Why it’s bad: Emails from the new provider may fail DMARC authentication.
How to fix it: Always:
- Add SPF includes
- Set up DKIM
- Test with tools before sending
10. Using a Shared Domain Instead of a Custom One
The mistake: Sending from @gmail.com or @yourESPdomain.com.
Why it’s bad: You can’t set DMARC policies on domains you don’t own.
How to fix it: Use a custom domain (e.g., you@yourdomain.com) and configure proper authentication.
Final Thoughts: Authentication = Trust
If you want your emails to reach inboxes and protect your brand from spoofing, you must avoid these common email authentication mistakes. Setting up and maintaining SPF, DKIM, and DMARC correctly is essential — and easier than you think with the right tools.
