Email Not Arriving? Fix Deliverability Issues

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The Email Deliverability Problem

You send an email. The recipient never sees it.

It either:

• Landed in spam
• Was rejected by the server
• Got lost somewhere in between

Email deliverability isn't automatic—it requires proper setup and ongoing attention.

Email Authentication Basics

Why Authentication Matters

Without authentication, anyone can send email claiming to be from your domain. Spammers abuse this constantly.

Authentication records prove to receiving servers that your emails are legitimate. Without them, servers are more likely to reject or spam your messages.

SPF (Sender Policy Framework)

SPF is a DNS record that lists which servers are authorized to send email for your domain.

How it works:

1. You publish an SPF record in DNS
2. When you send email, the receiving server checks the record
3. If the sending server is listed, SPF passes
4. If not, SPF fails

Example SPF record:

v=spf1 include:_spf.google.com include:sendgrid.net -all

This says: Google and SendGrid can send for this domain. Reject all others (-all).

Setting up SPF:

1. List all services that send email for you (Google Workspace, Mailchimp, etc.)
2. Get their SPF include statements from their documentation
3. Create one SPF record combining all includes
4. Add as a TXT record in DNS

Common mistakes:

• Multiple SPF records (only one allowed)
• Missing a sending service
• Too many DNS lookups (limit of 10)

DKIM (DomainKeys Identified Mail)

DKIM adds a cryptographic signature to emails, proving they haven't been modified.

How it works:

1. Your email server signs outgoing messages with a private key
2. You publish the public key in DNS
3. Receiving servers verify the signature
4. If valid, DKIM passes

Example DKIM record:

selector._domainkey.yourdomain.com TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSq..."

Setting up DKIM:

1. Your email provider generates keys
2. They give you a DNS record to publish
3. Add the TXT record to DNS
4. They sign your outgoing emails

Each sending service needs its own DKIM record.

DMARC (Domain-based Message Authentication)

DMARC tells receiving servers what to do when SPF or DKIM fail, and provides reporting.

How it works:

1. You publish a DMARC policy
2. Receiving servers check SPF and DKIM
3. If both fail, they follow your DMARC policy
4. They can send you reports on failures

Example DMARC record:

_dmarc.yourdomain.com TXT "v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com"

Policy options:

• p=none - Monitor only, don't take action (start here)
• p=quarantine - Send failures to spam
• p=reject - Reject failures outright

Setting up DMARC:

1. Start with p=none to monitor
2. Review reports to find legitimate email that fails
3. Fix issues found
4. Gradually move to p=quarantine then p=reject

Checking Your Current Setup

Online Tools

• MXToolbox - Check all records and blacklists
• Mail Tester - Send a test email, get a score
• DMARC Analyzer - Check DMARC specifically
• Google Admin Toolbox - Dig into DNS records

Basic Checks

1. SPF: dig TXT yourdomain.com or use MXToolbox
2. DKIM: dig TXT selector._domainkey.yourdomain.com
3. DMARC: dig TXT _dmarc.yourdomain.com

What to Look For

• All three records exist
• SPF includes all your sending services
• DKIM shows a valid public key
• DMARC has at least p=none

Common Deliverability Problems

Blacklisted IP/Domain

If your IP or domain is on a blacklist, many servers will reject your email.

Check: Use MXToolbox or MultiRBL to check blacklists.

Causes:

• Sending spam (intentionally or via compromised account)
• Shared IP with spammers (common on cheap hosting)
• Sudden large volume increase
• High bounce rates

Solutions:

• Request removal from specific blacklists
• Find and stop the spam source
• Switch to a dedicated IP or reputable ESP
• Improve list hygiene

High Bounce Rate

Sending to invalid addresses hurts your reputation.

Fix:

• Clean your list (remove bounces immediately)
• Use double opt-in
• Verify email addresses at signup
• Remove inactive subscribers

Spam Complaints

Recipients marking you as spam damages sender reputation.

Fix:

• Only email people who opted in
• Make unsubscribe easy and obvious
• Set proper expectations at signup
• Don't email too frequently

Content Issues

Spam filters analyze content for red flags.

Avoid:

• ALL CAPS
• Excessive punctuation!!!
• Spam trigger words ("free," "guaranteed," "act now")
• Image-only emails
• Misleading subject lines
• URL shorteners

Email Service Providers

Why Use an ESP

Using an Email Service Provider for marketing and transactional email provides:

• Pre-warmed IP addresses with good reputation
• Built-in authentication
• Bounce and complaint handling
• Analytics and deliverability monitoring

For Transactional Email

• SendGrid - Popular, reliable, good free tier
• Postmark - Excellent deliverability focus
• Mailgun - Developer-friendly
• Amazon SES - Cheap at scale, more DIY

For Marketing Email

• Mailchimp - User-friendly, good for small lists
• ConvertKit - Creator-focused
• Klaviyo - E-commerce focused
• ActiveCampaign - Advanced automation

Troubleshooting Workflow

Email Not Arriving at All

1. Check server logs for errors
2. Check spam folder
3. Verify DNS records (SPF, DKIM, DMARC)
4. Check blacklists
5. Test with different recipients/providers
6. Review bounce messages for clues

Going to Spam

1. Run through Mail Tester for specific issues
2. Check authentication (SPF, DKIM, DMARC)
3. Review content for spam triggers
4. Check sender reputation
5. Verify list quality

Intermittent Issues

1. Check if specific providers are affected
2. Review sending patterns (sudden spikes?)
3. Check for IP rotation issues
4. Monitor over time for patterns

Maintaining Good Deliverability

Ongoing Practices

• Monitor bounce rates (keep under 2%)
• Monitor spam complaints (keep under 0.1%)
• Clean lists regularly
• Warm up new IPs/domains gradually
• Keep authentication records updated

When Adding New Sending Services

1. Get their SPF include
2. Add to your SPF record
3. Set up their DKIM record
4. Test before going live

Regular Audits

Monthly:

• Check Mail Tester score
• Review bounce/complaint rates
• Check blacklist status

When issues arise:

• Full DNS audit
• Sending pattern review
• Content analysis

Blacklist Removal

What Are Blacklists?

Blacklists explained:

• Databases of IPs/domains known for spam
• Maintained by various organizations
• Receivers check against them
• Being listed hurts deliverability significantly

Common blacklists:

• Spamhaus (most influential)
• SURBL
• SpamCop
• Barracuda
• SORBS

Checking If You're Blacklisted

Tools:

• MXToolbox Blacklist Check
• MultiRBL.valli.org
• WhatIsMyIPAddress Blacklist Check

How to check:

1. Enter your domain or IP
2. Check multiple blacklists
3. Note which ones list you
4. Check listing reason

Getting Removed

Steps:

1. Identify the cause - Why were you listed?
2. Fix the issue - Stop spam, fix security
3. Request removal - Follow blacklist's process
4. Wait for review - Usually 24-48 hours
5. Monitor - Ensure you don't get relisted

Prevention:

• Maintain good sending practices
• Monitor for compromised accounts
• Use authentication records
• Keep bounce rates low

Content Issues That Cause Spam

Spam Trigger Words

Words to avoid:

• Free, guarantee, winner
• Act now, limited time
• Click here, buy now
• No risk, 100% satisfied
• All caps subject lines

Better alternatives:

• Use specific, descriptive language
• Focus on value, not urgency
• Professional tone
• Clear, honest messaging

Formatting Problems

Issues:

• Too many images, little text
• Excessive exclamation marks
• ALL CAPS text
• Poor HTML structure
• Broken links

Best practices:

• Balance text and images
• Professional formatting
• Proper HTML structure
• Test all links
• Mobile-friendly design

Sender Reputation

What Is Sender Reputation?

Definition:

• Score assigned to your sending domain/IP
• Based on sending history
• Affects inbox placement
• Managed by ISPs (Gmail, Outlook, etc.)

Factors affecting reputation:

• Bounce rates
• Spam complaints
• Engagement rates (opens, clicks)
• Sending volume consistency
• Authentication records

Building Good Reputation

Best practices:

• Start with small volumes
• Gradually increase sending
• Maintain low bounce rates
• Keep complaint rates low
• Use consistent sending patterns
• Authenticate properly

Warming up new domain/IP:

• Start with 50-100 emails/day
• Increase by 20% daily
• Focus on engaged recipients
• Monitor metrics closely
• Take 2-4 weeks to reach full volume

Testing Your Setup

Email Testing Tools

Mail Tester:

• Free deliverability test
• Scores 0-10
• Shows specific issues
• Provides recommendations

MXToolbox:

• DNS record checking
• Blacklist checking
• Email header analysis
• SPF/DKIM/DMARC validation

GlockApps:

• Inbox placement testing
• Multiple provider testing
• Detailed reporting
• Paid service

What to Test

Before sending:

• SPF record validity
• DKIM signature
• DMARC policy
• Blacklist status
• Content spam score

After sending:

• Inbox placement
• Spam folder placement
• Delivery rates
• Open/click rates
• Bounce rates

Troubleshooting Specific Scenarios

Scenario 1: Emails to Gmail Go to Spam

Common causes:

• Missing authentication
• Poor sender reputation
• High complaint rate
• Suspicious content

Fixes:

• Set up SPF, DKIM, DMARC
• Improve sender reputation
• Reduce complaints
• Review content

Scenario 2: Emails to Outlook Go to Spam

Common causes:

• Missing DMARC
• IP reputation issues
• Content filtering
• Sending pattern issues

Fixes:

• Implement DMARC
• Check IP reputation
• Review content
• Normalize sending patterns

Scenario 3: Transactional Emails Not Arriving

Common causes:

• Authentication missing
• IP reputation
• Content issues
• Rate limiting

Fixes:

• Use dedicated IP
• Authenticate properly
• Use reputable service
• Monitor delivery

Conclusion

Email deliverability issues are frustrating, but most problems are fixable with proper authentication and good sending practices.

Key takeaways:

• Set up SPF, DKIM, and DMARC
• Monitor bounce and complaint rates
• Maintain good sender reputation
• Test your setup regularly
• Use reputable email service providers

The bottom line: Most deliverability issues stem from missing authentication or poor sending practices. Set up proper authentication records, maintain good sending habits, and monitor your reputation. With proper setup, most emails will reach the inbox.

For more troubleshooting help, check out our website down checklist or learn about domain setup.