Email Reputation Score — How to Check & Improve Your Domain Reputation in 2026

Last updated: April 2026 · 16 min read

Every email you send carries an invisible score — a reputation calculated by Gmail, Outlook, Yahoo, and every other receiving mail server. This email reputation score determines whether your email lands in the inbox, the spam folder, or gets silently dropped. If you're not tracking it, you're flying blind.

This guide explains exactly what email reputation scores are, how they're calculated, how to check your domain reputation for free, and what to fix when your score is dragging your deliverability down.

What Is an Email Reputation Score?

An email reputation score is a composite rating that mailbox providers (Gmail, Outlook, Yahoo) assign to your sending domain and sending IP address. It's not a single number published by one authority — it's calculated independently by each provider based on dozens of signals. Think of it like a credit score for your email.

The score determines what happens when your email arrives at a receiving server:

The Six Factors That Determine Your Score

At MailCheck, we score domains on six DNS authentication factors. Here's what each one measures and why it matters:

1. SPF (Sender Policy Framework) — Does your domain declare which IPs can send email on its behalf? Missing or broken SPF is the #1 reason emails fail authentication.
2. DKIM (DomainKeys Identified Mail) — Does each email carry a cryptographic signature that verifies it wasn't modified in transit? DKIM alignment is critical for DMARC to pass.
3. DMARC (Domain-based Message Authentication, Reporting & Conformance) — Does your domain tell receivers what to do when SPF or DKIM fail? No DMARC = receivers guess, and they usually guess "spam."
4. MTA-STS (SMTP MTA Strict Transport Security) — Does your domain enforce encrypted TLS connections for email delivery? Prevents MITM attacks and is a positive reputation signal.
5. TLS-RPT (TLS Reporting) — Do you receive reports when TLS delivery fails? Detects interception and configuration errors.
6. BIMI (Brand Indicators for Message Identification) — Does your domain display a verified logo in inboxes? Requires DMARC enforcement and signals legitimacy.

How to Check Your Domain Reputation

There are several ways to check your email reputation, each covering different aspects:

1. DNS Authentication Score (Immediate Check)

The fastest way to assess your domain's email reputation is to check its DNS authentication posture. This is what our free tool measures:

# Check any domain's reputation score
curl -s https://korpo.pro/api/v1/check/example.com | python3 -m json.tool

# Just get the score number
curl -s https://korpo.pro/api/v1/check/example.com | python3 -c "import sys,json; print(json.load(sys.stdin)['score'])"

This returns a score from 0-100, plus detailed results for each of the six authentication protocols. Fixing the issues flagged here typically improves deliverability within minutes — DNS changes propagate fast.

2. Google Postmaster Tools (Gmail Reputation)

Google Postmaster Tools is Gmail's official dashboard for domain reputation. It shows:

• Domain reputation — High, Medium, Low, or Bad
• SPF/DKIM/DMARC pass rates — What percentage of your email passes each authentication check
• Spam complaint rate — How often users mark your email as spam (target: <0.1%)
• IP reputation — The sending IP's trust level
• Encryption — TLS adoption rate for your outgoing emails

Setup: Go to postmaster.google.com, add your domain, and add the verification TXT record to DNS. Data appears within 24-48 hours.

3. IP Reputation Check

Your sending IP address has its own reputation, separate from your domain. Check it with these tools:

4. Blacklist Monitoring

Being listed on a DNSBL (DNS-based Block List) is the fastest way to tank your reputation. Check your domain and IP against major blacklists:

# Check if your IP is on common blacklists
dig +short YOUR_IP.zen.spamhaus.org
dig +short YOUR_IP.bl.spamcop.net
dig +short YOUR_IP.dnsbl.sorbs.net

# Or use MailCheck's comprehensive blacklist guide
# https://korpo.pro/blog/email-blacklist-check

What Lowers Your Email Reputation Score

Understanding what hurts your reputation is the first step to fixing it. Here are the most common reputation killers, ranked by severity:

Critical Issues (Score Impact: -30 to -50 points)

• No DMARC policy — Without DMARC, receivers can't verify your emails are legitimate. Gmail and Outlook penalize domains without DMARC heavily.
• SPF hard fail (-all) — Wait, -all is correct. The critical issue is using +all or ?all, which tells receivers "anyone can send from my domain" or "I don't care about authentication."
• Domain on a blacklist — A single major blacklist listing can cut your reputation score in half.
• Hard bounce rate above 10% — Sending to invalid addresses destroys reputation fast.

Major Issues (Score Impact: -15 to -30 points)

• SPF lookup limit exceeded — More than 10 DNS lookups in your SPF record causes it to fail entirely. See our SPF flatten guide.
• DKIM misalignment — When your DKIM signing domain (d=) doesn't match your From header domain. Common with third-party senders.
• DMARC p=none with no progression — Having DMARC but never moving past p=none signals you don't enforce authentication.
• Missing rDNS (PTR record) — Your sending IP's reverse DNS doesn't match your HELO hostname.

Minor Issues (Score Impact: -5 to -15 points)

• Missing MTA-STS — 89% of domains lack MTA-STS. Having it is a positive reputation signal.
• Missing TLS-RPT — Without TLS reporting, you can't detect TLS delivery failures.
• Missing BIMI — Not a huge penalty, but BIMI presence signals domain maturity and legitimacy.
• DKIM key too short — 1024-bit DKIM keys are considered weak. Use 2048-bit.

How to Improve Your Email Reputation Score

Improving your email reputation follows a specific order — DNS authentication first, then sending practices, then monitoring:

Step 1: Fix DNS Authentication (Immediate Impact)

DNS changes propagate within minutes to hours, so this is where you get the fastest results:

1. Fix SPF — Include all sending services. Use ~all (softfail) or -all (hardfail). If you exceed 10 lookups, flatten your SPF record.
2. Enable DKIM — Set up DKIM on every sending service (Google Workspace, Mailgun, SendGrid, etc.). Use 2048-bit keys. Verify alignment.
3. Publish DMARC — Start with p=none and rua=mailto:dmarc@yourdomain.com. Monitor reports for 1-2 weeks, then graduate to p=quarantine and eventually p=reject.
4. Add MTA-STS — Publish the HTTPS policy endpoint and the DNS TXT record. See our MTA-STS guide.
5. Add TLS-RPT — One DNS TXT record: _smtp._tls.yourdomain.com TXT "v=TLSRPTv1;rua=mailto:tls-reports@yourdomain.com"
6. Add BIMI — After DMARC is at quarantine/reject. See our BIMI setup guide.

# Quick audit — check all six at once
curl -s https://korpo.pro/api/v1/check/yourdomain.com | python3 -m json.tool

# Check specific records
dig TXT yourdomain.com          # SPF
dig TXT selector._domainkey.yourdomain.com  # DKIM
dig TXT _dmarc.yourdomain.com  # DMARC
dig TXT _mta-sts.yourdomain.com  # MTA-STS
dig TXT _smtp._tls.yourdomain.com  # TLS-RPT
dig TXT default._bimi.yourdomain.com  # BIMI

Step 2: Improve Sending Practices (1-4 Weeks)

• Warm up new domains — Follow a 21-day warm-up protocol. Start at 20-30 emails/day, max 200/day. See our domain warm-up guide.
• Keep bounce rate below 5% — Verify email addresses before sending. Remove hard bounces from lists immediately.
• Keep spam complaint rate below 0.1% — Make unsubscribe easy. Never buy email lists. Use confirmed opt-in.
• Use a dedicated IP — Shared IPs carry other senders' reputation problems. A dedicated IP ($20-30/month from most ESPs) gives you full control.
• Set up rDNS — Your sending IP must have a PTR record that resolves back to your HELO hostname.

Step 3: Monitor Continuously (Ongoing)

Email reputation isn't set-and-forget. DNS records change, IPs get blacklisted, and best practices evolve. Set up monitoring:

# Automate reputation checks with the MailCheck API
# Run this weekly via cron
#!/bin/bash
DOMAINS=("yourdomain.com" "outreach.yourdomain.com" "send.yourdomain.com")
for d in "${DOMAINS[@]}"; do
  SCORE=$(curl -s "https://korpo.pro/api/v1/check/$d" | python3 -c "import sys,json; d=json.load(sys.stdin); print(d['score'])")
  echo "$(date): $d score = $SCORE"
  if [ "$SCORE" -lt 80 ]; then
    echo "WARNING: $d score dropped below 80!"
    # Send alert via email, Slack, etc.
  fi
done

Also set up:

• Google Postmaster Tools — Weekly dashboard review for Gmail-specific reputation
• DMARC RUA reports — Set up DMARC reporting to monitor which senders pass or fail authentication
• TLS failure alerts — TLS-RPT reports (configured above) alert you when TLS delivery is downgraded
• Blacklist monitoring — Check weekly against Spamhaus, SORBS, Barracuda, and 50+ other DNSBLs

Email Reputation vs. Deliverability — What's the Difference?

These terms are often confused but they measure different things:

Think of it this way: Reputation is the trust score that gets your email accepted by the receiving server. Deliverability is whether that accepted email lands in the inbox or the spam folder. Good reputation is necessary but not sufficient for good deliverability — you also need good content, clean lists, and proper sending patterns.

Common Email Reputation Problems (And How to Fix Them)

"My domain score is below 60"

This usually means missing or broken authentication records. Run a free check and fix the issues flagged in each section. Typically:

• No DMARC record → Add one immediately (DMARC setup guide)
• SPF +all or ?all → Change to ~all or -all
• DKIM not configured → Enable DKIM in your sending platform and publish the DNS record

"My emails started going to spam suddenly"

1. Check if your domain or IP was recently blacklisted — use our blacklist guide
2. Check if SPF/DKIM/DMARC records were accidentally changed or deleted
3. Review Google Postmaster Tools for spam complaint rate increases
4. Check if your sending volume spiked (seasonal campaigns can trigger rate limits)
5. Verify your SPF hasn't exceeded the 10-lookup limit — flatten if needed

"My reputation was good but has been declining"

1. Review DMARC aggregate reports for new senders that aren't authenticated
2. Check bounce rates — hard bounces over 5% damage reputation quickly
3. Monitor spam complaint rates in Postmaster Tools (target <0.1%)
4. Review email engagement — declining open/click rates signal declining reputation
5. Check if your dedicated IP has been reassigned or shared IP pool changed

"I'm on a blacklist — how do I get delisted?"

Each blacklist has its own delisting process. See our complete blacklist check and delisting guide. Key steps:

• Identify which list you're on (not all blacklists are equal)
• Fix the root cause (authentication issues, spam traps, compromised account)
• Submit a delisting request through the blacklist's website
• Set up monitoring to catch future listings early

Email Reputation Benchmarks by Industry

What's a "good" score depends on your industry, but here are general benchmarks:

Automate Reputation Monitoring with the API

Don't just check once — set up continuous monitoring. The MailCheck API makes this easy:

# Check a single domain
curl -s https://korpo.pro/api/v1/check/yourdomain.com

# Batch check multiple domains
curl -X POST https://korpo.pro/api/v1/batch \
  -H "Content-Type: application/json" \
  -d '{"domains":["company.com","outreach.company.com","send.company.com"]}'

# Parse the score programmatically
curl -s https://korpo.pro/api/v1/check/yourdomain.com | \
  python3 -c "
import sys, json
data = json.load(sys.stdin)
print(f'Score: {data["score"]}/100')
print(f'SPF: {"PASS" if data["spf"]["found"] else "MISSING"}')
print(f'DKIM: {"PASS" if data["dkim"]["found"] else "MISSING"}')
print(f'DMARC: {"PASS" if data["dmarc"]["found"] else "MISSING"}')
print(f'MTA-STS: {"PASS" if data.get("mta_sts",{}).get("found") else "MISSING"}')
print(f'BIMI: {"PASS" if data.get("bimi",{}).get("found") else "MISSING"}')
"

curl -s https://korpo.pro/api/v1/check/example.com | jq '.score'

The Complete Email Reputation Checklist

• SPF record published and includes all sending services (~all or -all)
• SPF lookup count is under 10 (flatten if needed)
• DKIM enabled on all sending platforms (2048-bit keys)
• DKIM d= domain aligned with From header domain
• DMARC p=none published with rua reporting address
• DMARC graduated to p=quarantine or p=reject
• MTA-STS policy published and accessible via HTTPS
• TLS-RPT reporting configured
• BIMI record published (after DMARC p=quarantine/reject)
• Reverse DNS (PTR) set on sending IPs
• Dedicated IP for outbound email (not shared)
• Domain warmed up (2-3 weeks for new domains)
• Sending volume under 200/day per domain for cold outreach
• Hard bounce rate below 5%
• Spam complaint rate below 0.1%
• Not listed on any major DNSBLs
• Google Postmaster Tools verified and monitored
• DMARC aggregate reports reviewed weekly
• Weekly automated reputation check via API
• Email list hygiene: remove bounces, inactive subscribers

Your email reputation score is the single most important factor in whether your emails reach the inbox. Start by running a free domain check to see where you stand, then work through the checklist above. Most domains can go from 50 to 80+ in a single afternoon of DNS fixes.

For ongoing monitoring, use the MailCheck API to automate reputation checks and catch issues before they affect your deliverability.