What Is Spam Score?
A spam score is a numeric rating that estimates how likely an email—or the domain sending it—is to be flagged as spam by inbox providers. Filters like Gmail, Outlook, and Yahoo evaluate hundreds of signals and assign weighted points; tools surface that math as a single score you can act on.
The catch: there is no single "spam score." SpamAssassin scores higher = worse. Mail-Tester and Postmark score higher = better. Google Postmaster reports a categorical reputation rather than a number. Moz Spam Score is an SEO metric that has nothing to do with email at all. Treating a 7 the same across tools will lead you to the wrong fix.
What a Spam Score Tells You
- Probability your email lands in spam — given current content, headers, and authentication.
- Which specific signals are dragging it down — a good tool itemizes every rule that fired.
- Whether the problem is the message or the sender — content fixes are minutes; reputation fixes are weeks.
- It does NOT guarantee delivery — every recipient's filter is slightly different, and engagement history matters.
The fastest way to see your own number is to run our free spam score checker—it returns a SpamAssassin-style score with itemized issues in under a minute.
Scoring Scales by Provider
Before you panic at a number, find out which scale the tool is using. Here are the four you'll actually encounter in practice:
| Tool / Provider | Scale | Direction | "Good" Threshold |
|---|---|---|---|
| SpamAssassin | 0 → unbounded | Higher = worse | < 5.0 delivered |
| Mail-Tester | 0 → 10 | Higher = better | 8/10+ |
| Postmark | 0 → 10 | Higher = better | 9/10+ |
| Google Postmaster | Categorical | High / Medium / Low / Bad | High or Medium |
| Sender Score (Validity) | 0 → 100 | Higher = better | 80+ |
| Moz Spam Score (SEO) | 0 → 17 | Higher = worse | Not email-related |
SpamAssassin (and tools built on it)
The open-source filter that runs on a huge share of receiving mail servers. Each rule that fires (a trigger word, bad HTML, missing DKIM) adds a positive or negative weight; the sum is your score. The default delivery threshold is 5.0—anything above is bounced or filtered by most servers running it. Aim for 0–2 to stay safe across differently-tuned setups.
Mail-Tester & Postmark
Both invert SpamAssassin's output into a 0–10 score where 10 is perfect. They add their own checks—DKIM/SPF/DMARC alignment, blacklist lookups, broken HTML—and subtract from 10 for each issue. Postmark's scale tends to penalize more aggressively than Mail-Tester for the same content, so "8 on Mail-Tester" is not the same as "8 on Postmark."
Google Postmaster Tools
Free data from Google about how Gmail actually treats your sending domain and IP. It reports Domain Reputation and IP Reputation as High / Medium / Low / Bad—a categorical version of a spam score that reflects real delivery behavior to Gmail users. It's the single most authoritative signal for B2B and B2C senders, because Gmail handles roughly a third of business email.
Sender Score (Validity / Return Path)
A 0–100 reputation score for a sending IP, calculated from a panel of ISP feedback, complaint rates, and spam-trap hits. It's sender-level, not message-level: it won't tell you about a single email's content, but it's a strong indicator of long-term inbox placement.
Most readers arrive here after seeing a number from one of these tools. The right response depends on which scale produced it—so always start by writing down the tool name next to the score before deciding what to fix.
Domain Spam Score vs Email Spam Score
"Domain spam score" is the most overloaded term in deliverability. Three different things use that label, and confusing them will send you down the wrong rabbit hole:
1. Sending-domain reputation (email deliverability)
What inbox providers think of your sending domain based on engagement, complaints, bounces, and authentication. Reported by Google Postmaster Tools as Domain Reputation, by Microsoft via SNDS, and indirectly by Sender Score. This is the one that affects whether your campaigns reach the inbox. If someone says "my domain spam score is bad" in a deliverability context, this is almost always what they mean.
2. Message-level spam score (per-email)
A score for one specific message you're testing, produced by SpamAssassin, Mail-Tester, Postmark, or our spam checker tool. Reflects content, formatting, headers, and authentication on that single email. Useful pre-flight check; doesn't describe your domain.
3. Moz Spam Score (SEO — unrelated to email)
A 0–17 score Moz calculates from a domain's backlink profile and on-page signals to predict the chance Google penalizes it. It has no effect on email deliverability. If your Moz Spam Score is 8 but your Google Postmaster Domain Reputation is High, your emails will still hit the inbox. People googling "domain spam score" often land on Moz content and assume it matters for sending—it doesn't.
Quick decision rule
- Worried about inbox placement? Check sending-domain reputation (#1) and message-level score (#2).
- Worried about SEO rankings? Look at Moz Spam Score (#3)—but it's a directional signal, not a verdict.
- Worried about being on a blacklist? That's a separate check—see our email blacklist guide.
What Affects Your Spam Score
Every scoring system weighs these five categories. The exact weights vary—SpamAssassin exposes them in its 50_scores.cf file; commercial tools keep theirs private—but the categories are universal:
1Authentication (typically ~30% of weight)
Whether SPF, DKIM, and DMARC are configured and align. A missing DKIM signature alone can add 2.0+ points on SpamAssassin. DMARC quarantine/reject policies on misaligned mail are an instant fail at many providers. This is the largest single fixable lever for most senders.
2Sender reputation (typically ~25% of weight)
History of your domain and sending IP: complaint rate, bounce rate, blacklist appearances, and engagement metrics. This is the slowest signal to change—it typically reflects 30–90 days of behavior—and the hardest to fake. Postmark and Mail-Tester will dock you here if your domain is on a public blacklist like Spamhaus or SORBS.
3Content (typically ~20% of weight)
Spam trigger words, ALL CAPS, excessive punctuation, money symbols, and suspicious phrases. Content rules are individually small (0.1–1.0 points each on SpamAssassin) but stack quickly. The good news: content is the easiest category to fix in a single edit pass.
4Engagement signals (typically ~15% of weight)
Open rates, reply rates, "mark as not spam" actions, and forward rates—weighted especially heavily by Gmail. Low engagement on previous sends pulls future sends toward the spam folder regardless of content. You can't raise engagement on a single email, but you can prune unengaged subscribers to raise your aggregate rates.
5List hygiene & technical headers (typically ~10% of weight)
Bounce rate from invalid addresses, presence of spam traps in your list, mismatched From/Reply-To addresses, missing List-Unsubscribe header, broken HTML, image-only emails, and shortened links. Dirty lists are the single biggest source of slow reputation decay— email verification fixes this category in one pass.
How to Run an Email Spam Score Test
There are two common test methodologies, and a thorough audit uses both:
Paste-in checkers (fast, content-focused)
Paste your subject line and body HTML into a tool that runs SpamAssassin and related rules. Best for catching content issues before you wire up sending. Examples: our spam score checker, GlockApps, Mailtrap's built-in tester.
Best for: template QA, copy review, last pre-flight check before sending.
Seed-list tests (slow, deliverability-focused)
Send your email to a curated list of test inboxes at Gmail, Outlook, Yahoo, AOL, and corporate domains, then check which folder it landed in. Examples: Mail-Tester (single inbox + SpamAssassin), GlockApps (multi-inbox), Litmus, Email on Acid.
Best for: validating that authentication and reputation are working at real ISPs—not just on paper.
Free spam score test, no signup
Paste an email subject and body, get an itemized SpamAssassin-style report with every rule that fired and the points it cost you. No account required.
Check spam scoreWhat Is a Good Spam Score?
Because direction varies by tool, here's the actionable breakdown for each scale:
SpamAssassin: aim for 0–2
- • 0–2: Excellent — well below any threshold
- • 2–4: Acceptable — review flagged rules
- • 4–5: Marginal — some servers will filter
- • 5+: Most servers reject or quarantine
Mail-Tester: aim for 8+
- • 9–10: Excellent
- • 8–9: Good — minor cleanup possible
- • 6–8: Real risk — fix flagged issues
- • <6: Will hit spam at most ISPs
Postmark: aim for 9+
- • 10: Perfect (rare with real content)
- • 9: Good — typical for clean templates
- • 7–8: Mixed — investigate before sending bulk
- • <7: Don't send — fix first
Google Postmaster: aim for High
- • High: ideal — Gmail trusts your domain
- • Medium: usable — pockets of filtering
- • Low: significant spam folder placement
- • Bad: most mail rejected — fix urgently
Translation cheat sheet
Rough equivalents when comparing across tools (these aren't exact—reputation shifts the curve—but they're close enough for triage):
- • SpamAssassin 0–2 ≈ Mail-Tester 9–10 ≈ Postmark 9–10 ≈ Google Postmaster High
- • SpamAssassin 3–4 ≈ Mail-Tester 7–8 ≈ Postmark 7–8 ≈ Google Postmaster Medium
- • SpamAssassin 5+ ≈ Mail-Tester <6 ≈ Postmark <7 ≈ Google Postmaster Low/Bad
How to Lower Your Spam Score
Run through this playbook in order—earlier steps are faster wins, later steps take weeks. Each step maps to one of the weighted categories above.
1Fix authentication first (hours, biggest single drop)
Publish SPF, DKIM, and DMARC records that align with your From domain. Use a DMARC report parser (Postmark's free DMARC weekly emails are a good start) to confirm alignment is actually passing. This single fix often drops SpamAssassin scores by 3+ points and moves Google Postmaster reputation up a tier within a week.
2Rewrite content trigger words (minutes)
Replace "FREE," "Act now," "Limited time," "Guaranteed," and other classic triggers. Remove ALL CAPS, multiple exclamation marks, and $$$ symbols. See our full spam trigger word list for the categories that fire most often.
3Fix HTML and headers (minutes)
Aim for at least 60% text by character count, not images. Add alt text to every image. Remove broken tags. Ensure From, Reply-To, and Return-Path all use the same authenticated domain. Add a List-Unsubscribe header (mandatory at Gmail and Yahoo for senders >5,000/day since 2024).
4Verify your list (hours, prevents weeks of damage)
Bounce rates above 2% damage sender reputation faster than any single bad email. Run your list through email verification before every campaign over a few months old. This also pulls out spam traps, which can blacklist a domain instantly. Verification is the single highest-ROI deliverability investment for most senders.
5Check public blacklists (10 minutes)
A single Spamhaus or SORBS hit can wipe out a Mail-Tester score. Run a blacklist check on your domain and IP, then follow the delisting process for any RBL where you appear.
6Prune disengaged subscribers (a sending cycle)
Subscribers who haven't opened in 6+ months tank your engagement metrics and feed Gmail's "low engagement = probable spam" heuristic. Move them to a re-engagement sequence; remove anyone who still doesn't open. A smaller, engaged list outperforms a larger, dead one within two sends.
7Warm up cold domains or IPs (2–6 weeks)
A new domain or IP has no reputation, and sending 10,000 emails on day one looks like a spam blast. Start with 50–100/day to engaged recipients and double weekly until you reach target volume. Postmark and SendGrid publish warmup schedules you can copy directly.
Expected impact, ranked
In our experience working with senders fixing deliverability issues: authentication + list verification together resolve roughly 70% of "why is my score bad" cases. Content rewrites resolve another 15–20%. The remaining 10% is reputation damage that needs the slow fix (steps 6 and 7).
Frequently Asked Questions
What is a good spam score?
How is domain spam score different from email spam score?
Does Moz Spam Score affect email deliverability?
How often should I check my spam score?
Can I lower my spam score quickly?
What does a spam score checker actually measure?
Find out your spam score in 60 seconds
Paste your email content into our free spam score checker for an itemized report, then verify your list to fix the reputation side too.