Your open rates look solid. Your click-through rates are industry-leading. But a chunk of your highest-value prospects never see your messages at all.

I hear this all the time. A SaaS marketing team discovered their product demo emails were performing well across consumer email providers, but enterprise prospects using corporate email systems weren't converting. The issue? Incomplete email authentication that was silently filtering their messages.

You've probably experienced this without realizing it. Your B2B campaigns underperform compared to B2C with identical content. Microsoft 365 and Google Workspace domains show consistently lower engagement. Time-sensitive campaigns experience mysterious delivery delays. Your "engaged" segments miss subscribers who should be highly active.

This problem is more common than you think, and it's costing revenue in ways that don't show up in your reporting.

How authentication failures hide:

Authentication failures are hard to spot because they don't bounce—the emails just disappear.

Here's what to watch for:

• B2B campaigns underperform compared to B2C with identical content

• Microsoft 365 and Google Workspace domains show consistently lower engagement

• Time-sensitive campaigns experience mysterious delivery delays

• Your "engaged" segments miss subscribers who should be highly active

The three authentication records you need:

Think of these as your email's proof of identity. When properly configured, they tell receiving servers your messages are legitimate.

SPF Records: Lists which servers can send email from your domain. If your email service provider isn't listed, receiving servers flag your messages as suspicious.

DKIM Signatures: A digital signature that proves your email actually came from your domain and hasn't been tampered with during delivery.

DMARC Policies: Instructions for what to do when emails fail the other checks, plus reports about attempted fraud or misconfigurations.

10-minute authentication check:

You can audit these without technical skills:

Check SPF: Go to mxtoolbox.com/spf.aspx and enter your sending domain. Your email service provider should appear in the results.

Test DKIM: Send a test email to Gmail. Click the three dots → "Show original" → search for "DKIM." Look for "DKIM=pass."

Verify DMARC: Visit mxtoolbox.com/dmarc.aspx and enter your domain. Even "p=none" is better than no policy.

A fintech startup ran this check and found their nurture sequences had no DKIM authentication. After fixing it, their enterprise lead conversion improved 23% in two weeks.

How to get these fixed?

Don't worry, you don't need to become a DNS expert.

SPF and DMARC: Your IT team adds these to your domain's DNS records. Your email service provider's documentation (SFMC, Braze, Klaviyo, etc.) shows exactly what to include. Contact your tool's support if you have questions about accessing records.

DKIM: Requires setup in both your email platform and DNS records. Search your ESP's help docs for "email authentication setup."

Three common problems:

I see these issues repeatedly, even with experienced marketing teams:

Outdated SPF Records: You switched email platforms but never updated your SPF record to include the new service.

Missing DKIM: Your marketing emails have DKIM, but transactional emails don't—creating inconsistent authentication.

Weak DMARC: You have "p=none" for monitoring but never upgraded to actual protection.

Talking to your IT team:

Skip vague requests. Be specific about what you need:

Instead of: "Our emails aren't getting delivered properly."

Try: "Our SPF record is missing [ESP name], DKIM isn't configured, and we need a DMARC policy with p=none. Can you add these DNS records?"

This approach gets faster results because your IT team knows exactly what to implement.

Your action plan:

Here's how to tackle this systematically:

1. Run the authentication check to identify what's missing

2. Find your ESP's setup documentation for the specific records you need

3. Request specific DNS updates from your technical team

4. Test after implementation using the same tools

5. Monitor problematic domains over the next few weeks

Authentication issues are completely preventable but often undetectable until you look for them. If you see unexplained performance differences between domains, authentication might be the missing piece.