Email Deliverability Tester

Check SPF, DKIM, DMARC, and MX records to ensure your emails reach the inbox.

What It Checks

• SPF: Sender Policy Framework (authorized sending IPs)
• DKIM: DomainKeys Identified Mail (email signing)
• DMARC: Domain-based Message Authentication (policy enforcement)
• MX Records: Mail server configuration
• Blacklists: Check if domain/IP is on spam lists
• DNSSEC: DNS security for email records

Quick Test

1. Go to Email Deliverability Tester
2. Enter your domain (example.com)
3. Click "Test" — see pass/fail results
4. Follow recommendations to fix issues

SPF (Sender Policy Framework)

Purpose: Lists IP addresses authorized to send email for your domain.

Example SPF Record:

Mechanisms:

• +all — Allow all (never use — spam risk!)
• ~all — Soft fail (recommended — mark as spam if from unauthorized IP)
• -all — Hard fail (reject if not authorized)

Common Issue: Too many DNS lookups (max 10). Use `ip4:` instead of nested includes when possible.

DKIM (DomainKeys Identified Mail)

Purpose: Cryptographic signature proves email wasn't tampered with.

How It Works:

1. Your mail server signs outgoing emails with private key
2. Public key published in DNS (selector._domainkey.example.com TXT record)
3. Receiving server verifies signature using public key

Common Selectors: google, default, k1, s1, dkim

Check Your DKIM: Tool queries default._domainkey.yourdomain.com TXT record

DMARC (Email Policy)

Purpose: Tells receiving servers what to do if SPF/DKIM fail.

Example DMARC Record:

Policy Options:

• p=none — Monitor only (get reports, don't block)
• p=quarantine — Send to spam folder
• p=reject — Block completely

Best Practice: Start with `p=none`, analyze reports for 2 weeks, then move to `p=quarantine` or `p=reject`.

MX Records

Specifies mail servers for your domain. Tool checks:

• At least 1 MX record exists
• All MX hosts resolve to valid IPs
• Multiple MX records for redundancy (recommended)
• Priority values are set (lower = higher priority)

Example:

example.com.   IN MX 10 mail1.example.com.
example.com.   IN MX 20 mail2.example.com.

Blacklist Check

Tool checks your domain/IP against 50+ spam blacklists:

• Spamhaus ZEN
• Barracuda
• SURBL
• URIBL

If blacklisted:

1. Identify why (compromised server, spam complaints, etc.)
2. Fix root cause
3. Request delisting (each blacklist has removal process)
4. Consider switching to dedicated IP or transactional email service

Common Issues & Fixes

Best Practices

• ✅ Implement all three: SPF + DKIM + DMARC
• ✅ Use DMARC reports to monitor (rua= email address)
• ✅ Keep SPF under 10 DNS lookups
• ✅ Rotate DKIM keys annually
• ✅ Use dedicated IP for high-volume sending
• ❌ Don't use +all in SPF (security nightmare)
• ❌ Don't go straight to p=reject (test withp=none first)