Free Email Spam Checker

You’ve written the campaign. The list is clean. The send time is scheduled. And then the email lands in spam.

It’s a frustrating scenario, and it happens more often than it should, not because of authentication issues or list quality, but because something in the content itself triggered a filter. A certain phrase in the subject line. Too many links. An image-heavy layout with almost no text. These are things you can catch before you send, if you know what to look for.

This free email spam checker analyzes your content against the same rules and signals that spam filters use. Paste your email, get a score, and see what’s flagging, while there’s still time to fix it.

How the email spam checker works

Paste your subject line and email body into the tool. The checker runs your content through a scoring engine that evaluates a range of spam filter signals, then returns a score and a breakdown of the specific issues found.

The score runs from 0 to 100. Lower is better. Here’s roughly how to interpret the ranges:

0–30 (Safe): Your content is unlikely to trigger filters based on these checks. That doesn’t mean delivery is guaranteed, authentication, sending reputation, and engagement history also factor in, but content isn’t working against you.

31–60 (Risky): There are signals in your content that some spam filters will flag. Depending on your sending reputation and the strictness of the receiving server, this range can go either way. Worth addressing before sending.

61–100 (Spam): Multiple strong spam signals are present. At this score, expect significant filtering across major mailbox providers. Fix the flagged issues before this email goes anywhere.

What spam filters actually look for

Modern spam filters are more sophisticated than a list of banned words, but that list still exists, and it still matters. Here’s a breakdown of the main content factors the checker evaluates:

Spam trigger phrases. Certain words and phrases carry a disproportionate spam signal because they’ve been overused by bad actors. “Free,” “guaranteed,” “act now,” “limited time offer,” “click here”, these aren’t inherently evil, but they accumulate. One instance of “free” in a professional email isn’t a problem. “Free free free” in a subject line that also includes “guaranteed” and “act now” definitely is.

Subject line patterns. ALL CAPS, excessive punctuation (!!!), and misleading subject lines are classic spam signals. Subject lines that don’t match the email body content are also flagged by some filters as deceptive.

Text-to-HTML ratio. An email that’s 90% images with a few lines of text looks, to a filter, like someone trying to hide content from text-based scanning. Aim for a healthy proportion of actual text relative to your HTML markup and images.

Link density. Too many links relative to the amount of text, or links that resolve to a different domain than they appear to, are red flags. Shortened URLs can also trigger filters, especially in emails, because they obscure the destination.

Broken or missing elements. Emails missing a plain-text version, or with malformed HTML, can score higher than they should. Most reputable ESPs generate a plain-text version automatically, but if you’re building HTML emails by hand, it’s worth checking.

Spam score vs. spam folder: an important distinction

A spam score measures the likelihood that spam filters will flag your content. It’s a meaningful signal, but it’s not the whole story.

Mailbox providers like Gmail, Outlook, and Apple Mail use spam scores as one input among many. Your sending reputation, built from engagement rates, complaint rates, and sending consistency over time, often carries more weight than content scoring alone. A sender with excellent reputation can get away with a higher spam score. A new domain with no reputation gets much less benefit of the doubt.

This is why content scoring is most useful as a relative tool, not an absolute one. If two versions of your email score 20 and 55 respectively, the 20 is clearly better. Whether a 20 goes to inbox for your specific domain depends on factors outside the content.

I’ve seen senders obsess over getting their spam score to zero while ignoring a complaint rate that was quietly destroying their reputation. Both matter. Content is just the piece you can fix before you hit send.

Common issues and how to fix them

High-scoring subject line. Read it out loud. Does it sound like something you’d say to a colleague, or does it sound like an infomercial? Strip out superlatives, urgency phrases, and excessive punctuation. Test multiple variations if you have time.

Too many spam trigger words in the body. Look at the specific phrases flagged in the report and consider whether they’re necessary. Sometimes a synonym works just as well and carries none of the baggage. “No cost” instead of “free.” “Get in touch” instead of “click here.”

Poor text-to-image ratio. Add more actual text to the email, or reduce the number of images. If your design requires a certain image-heavy layout, make sure the alt text is filled in, it contributes to text content and helps with accessibility too.

Too many links. Audit your links. Are all of them necessary? Every additional link adds a small spam signal. Combine links where you can, remove ones that aren’t serving a clear purpose.

Missing unsubscribe link. This one’s non-negotiable. A missing unsubscribe link is both a spam signal and, depending on your jurisdiction and sending volume, a legal requirement under CAN-SPAM, GDPR, and other regulations.

Frequently asked questions

Does a low spam score guarantee my email lands in the inbox?

No. Content scoring is one factor in deliverability. Your domain’s sending reputation, authentication setup (SPF, DKIM, DMARC), list quality, and engagement history all contribute. A low spam score removes content as a barrier, the other factors still apply. Use our free Email Deliverability Test to check your authentication alongside your content.

Should I check every email before sending?

For broadcast campaigns and newsletters: yes, it’s worth the two minutes. For transactional emails with established templates, a periodic check when you make template changes is sufficient. Where spam scoring pays off most is for new campaigns, new templates, or anything going to a cold or warmed list.

What’s the difference between this and a deliverability seed test?

A seed test sends a real email to test accounts at major mailbox providers and reports on inbox vs. spam placement. This tool checks your content before you send; no email goes anywhere. They serve different purposes. Use this tool to fix content issues proactively; use a seed test to validate actual inbox placement.

The tool flagged a phrase I use all the time. Do I have to remove it?

Not necessarily. Context matters. A single instance of a flagged phrase in an otherwise clean email is rarely decisive. The checker flags patterns and accumulations; if one phrase is flagged and your overall score is low, it’s probably fine. If you have ten flagged phrases and a score of 70, the cumulative weight is the problem.

Can I test HTML email code?

Yes. Paste the full HTML code of your email, the checker evaluates both the text content and HTML structure. This is the most thorough way to test, since it catches things like poor text-to-HTML ratio, excessive links, and missing elements that might not be visible if you only paste plain text.

How accurate is the spam score?

The score is a close approximation of rule-based spam filter logic. It’s most accurate for older, content-based filters. Modern machine learning filters at Gmail and others don’t publish their rules, so no tool can perfectly replicate them. That said, reducing your content spam score consistently correlates with better deliverability outcomes. Think of it as a necessary but not sufficient condition.

Content is the part of deliverability you control in real time, right up to the send button. Getting your spam score down is a good habit, but it works best when your authentication is also solid. If you haven’t checked your SPF, DKIM, and DMARC setup recently, the Email Deliverability Test will show you where you stand in about 30 seconds.

For Alterable users running real-time personalized campaigns, authentication and content quality both matter for each individual send. The tool on this page exist to help you close the gaps before they affect results.

Our spam testing tool provides automated analysis based on SpamAssassin rules and should be used for guidance only. While we strive for accuracy, we cannot guarantee delivery to inbox across email providers, complete detection of all spam triggers, or results matching actual email provider behaviors. Email delivery success depends on multiple factors beyond content analysis, and results may include false positives or negatives. Always test with your specific email service provider before sending important communications.