Test Your Email for Common Spam Signals
Paste in a subject and your email content. Get a transparent Content Risk Score, see what could be improved, and export a simple report.
What Is an Email Spam Checker?
An email spam checker analyzes an email's subject, body, links and HTML to highlight patterns commonly associated with spammy messages. It is a pre-send QA step — like a linter for email copy. A good checker never claims to predict real inbox placement because that decision is dominated by reputation, authentication, engagement and infrastructure, but it does help you rewrite copy that screams "mass blast", fix broken HTML, and remove constructs that spam filters have historically distrusted.
How Does an Email Spam Checker Work?
MailCannon's spam checker works entirely in your browser. It parses your subject and your email content (plain text or HTML), then runs a list of deterministic rules. Each finding has a category, a severity (critical / warning / good practice), a short recommendation and a score impact. The per-category scores are blended with fixed weights — Subject 22%, Content 24%, Links 20%, HTML 22%, Formatting 12% — to produce an overall 0–100 Content Risk Score. No AI request is required and nothing is uploaded to our servers.
What Makes an Email Look Like Spam?
- All-uppercase subjects or walls of ALL CAPS body text.
- Aggressive punctuation — stacks of !!! or ???.
- Classic trigger phrases layered together, especially when combined with urgency and high-risk claims.
- Misleading subjects that don't match the email body.
- Suspicious HTML such as scripts, iframes, forms, hidden text, off-screen CSS or on* event handlers.
- URL red flags — plain HTTP,
javascript:links,data:URLs, 20+ different domains or absurdly long tracking strings. - Extreme image-to-text ratio — images with a handful of hidden words used to try to evade filters.
What the Checker Analyzes
Common Email Spam Triggers
The checker looks for dozens of phrases commonly overused in promotional, aggressive or misleading copy — things like act now, click here, 100% guaranteed, free money, no risk, urgent, last chance, congratulations and phishing-adjacent wording like verify your account or unusual activity.
Important: one word never decides anything. The important thing is the pattern. If your email combines multiple trigger phrases, heavy punctuation, ALL CAPS, a misleading subject and suspicious URLs, that combination moves your score up; a single honest use of "free" in a genuine offer is usually fine.
How to Improve Email Deliverability
- Authenticate everything. Publish valid SPF, DKIM and DMARC records. DMARC enforcement protects both you and your recipients.
- Send from a warm, reputable IP / domain. Never blast cold traffic from a brand new domain with no history.
- Keep your list clean. Remove hard bounces immediately, honor unsubscribes within the legally required window, and re-engage stale subscribers carefully.
- Write honestly. Subject lines should match bodies. Don't FOMO-peddle urgency that isn't real. Match the promise of the subject.
- Use standard, lightweight HTML. Tables + inline styles are still the safest pattern. Avoid script tags, iframes, forms, display:none tricks.
- Always send both parts. A text/plain fallback next to your text/html version is the expected pattern.
- Test, then send. Run the checker, then email real test addresses across providers. Big sends deserve seed testing.
Does Spam Score Affect Inbox Placement?
It can contribute to it, but content is only one lever. Think of spam filtering like a credit score: a late payment here or there won't ruin you, but a history of late payments, high utilization and new credit inquiries will drag you down. Similarly: one slightly pushy subject line won't sink a reputable sender, but the same subject on a zero-reputation domain with no DKIM and a complaint-ridden IP will almost certainly land in spam. Use a spam checker to find the obvious content mistakes, then invest the real engineering effort in authentication, list quality and sender reputation — those are the things that actually move the needle on long-term deliverability.
Email Authentication and Deliverability
Long before any content scan runs, mailbox providers look at who is sending the mail and whether the message is authenticated. SPF tells receivers which servers are allowed to send from your domain. DKIM cryptographically signs each message so it cannot be tampered with in transit. DMARC tells receivers what to do when SPF or DKIM fails, and lets you receive reports to see who is (or isn't) sending on your behalf. Configure these first. After authentication comes domain and IP reputation: how long has your sending domain existed, how many complaints and bounces does it generate, are mailbox providers currently blocking or throttling you? None of this is visible to a content checker, which is why any checker must be honest about its limitations.
How to Test an Email Before Sending
- Run a spam check. Paste the subject + body into this tool and clear any high-severity findings you agree with.
- Send to real test inboxes. Gmail, Outlook, Outlook desktop, Apple Mail and Yahoo at minimum. Open them on web and mobile and compare rendering.
- Check your auth. View the original message headers and confirm SPF passes, DKIM passes and DMARC is aligned.
- Click your links. Do they go where they say? Are they on your verified custom tracking domain? Do they redirect cleanly?
- Look at images. Are they loading over HTTPS? Do they have alt text? Is the email still readable without images?
- Try unsubscribe. Does the one-click unsubscribe header work if your sender supports it? Does the footer link take you somewhere sensible within one click?
- Measure the send on a small sample first. If this is a new template or a new list, warm it up on a small slice and watch complaints and blocks before the big blast.