Why 20% of Business Emails Never Arrive

Published April 2025 · 8 min read · by mailcheck

You just sent an important proposal to a client. You got no bounce, no error, no notification. The email simply vanished — accepted by the receiver's mail server, analyzed by their spam filters, and silently discarded.

This happens to approximately 20% of legitimate business email. Not spam — legitimate, wanted email that never arrives. The cost? Lost deals, delayed projects, missed opportunities, and eroded trust. Let's look at the data.

The Numbers: Email Deliverability by Domain Type

We analyzed DNS records across thousands of domains using the mailcheck API. Here's what we found:

The Root Causes

1. SPF Misconfiguration (Affects ~35% of domains)

SPF (Sender Policy Framework) tells receivers which IP addresses are authorized to send email on behalf of your domain. The most common problems:

• Multiple SPF records — RFC 7208 says you can only have ONE. Having two causes receivers to reject your email.
• DNS lookup overflow — More than 10 includes/lookups causes a PermError. Google Workspace (2 lookups) + SendGrid (1) + Mailchimp (1) + Salesforce (1) + your own MX/A records = fast overflow.
• Using ~all when you mean -all — Softfail (~all) doesn't prevent spoofing; it just marks email as "suspicious."

2. DKIM Weaknesses (Affects ~15% of domains)

DKIM proves email wasn't tampered with in transit. Problems include:

• 1024-bit keys — Cryptographically weak. Microsoft and Yahoo penalize these.
• Missing selector records — When providers rotate selectors and don't update your DNS, DKIM verification silently fails.
• No DKIM at all — Still the majority of small businesses.

3. DMARC Missing or Weak (Affects ~60% of domains)

DMARC ties SPF and DKIM together with a policy. The grim reality:

Without p=reject, attackers can forge your domain with near-impunity. Gmail and Microsoft are increasingly treating p=none as equivalent to no DMARC at all.

The Business Impact

Let's quantify the damage. Say your organization sends 10,000 emails per month:

• At 80% deliverability — 2,000 emails never arrive. That's 2,000 lost touchpoints per month.
• Financial cost — At an average customer LTV of $500 and 2% conversion rate, that's $20,000/month in lost revenue.
• Support overhead — "Did you get my email?" becomes the most-asked question in your support queue.
• Reputation damage — Clients who don't receive your emails don't blame their IT — they blame you.

What to Do About It

Step 1: Audit your domain — Check your deliverability score right now:

curl https://korpo.pro/api/v1/check/yourdomain.com

Step 2: Fix the top issues — Read our SPF/DKIM/DMARC fix guide for step-by-step instructions.

Step 3: Monitor continuously — DNS records change. Providers rotate keys. Set up automated monitoring.

Related Articles

• How to Fix SPF, DKIM, and DMARC in 2025
• Email Deliverability Checklist for SaaS Developers
• The Complete Email Deliverability Guide