20 Words That Kill At Least When It Comes to Spam Filters

Understanding the Spam Filter Battlefield

Every day, thousands of newsletters, product updates, and editorial pieces race across the internet, hoping to land in the inbox rather than the spam folder. While spam filters have become smarter, they still rely on a handful of trigger words to catch unwanted mail. If your e‑zine contains any of these high‑score terms, it will likely accumulate points and be pushed to the junk folder or even blocked outright.

Spam filters such as SpamAssassin score incoming mail by scanning for patterns. A single instance of a risky word might add a fraction of a point, but a string of them can push a message past the threshold. That threshold varies by provider, but most major ISPs and email clients flag messages that score over five points as spam. Understanding which words carry the heaviest penalties is essential to keep your content visible.

The list below isn’t exhaustive, but it covers the most common culprits that appear in headlines, calls to action, and promotional blurbs. These words are flagged because they often appear in marketing emails that users report as spam. Even if your intent is genuine, the filter will see the same pattern.

• amazing
• cancel at any time
• check or money order
• click here
• congratulations
• dear friend
• e‑mail marketing
• for only ($)
• free (including toll‑free)
• great offer
• guarantee
• increase sales
• order now
• promise you
• risk free
• special promotion
• this is not spam
• to be removed
• unsubscribe
• winner

  Take the time to scan your upcoming issue for any of these terms. Removing or rephrasing them can shave several points off your score. A single “free” in a headline can add up quickly if repeated throughout a long article. By keeping the language natural and audience‑focused, you lower the risk that a filter will mistake your legitimate message for a sales pitch.

  Spam filters are evolving, yet the basic logic remains: words that appear frequently in unsolicited mail carry weight. By staying aware of the most common high‑score words, you can start building a cleaner, more inbox‑friendly email. The next step is to learn how to rewrite or mask these terms without sacrificing clarity.

  Cutting Down the Spam Score: Practical Tips

  Once you know the words to watch, the real work begins: reshaping your content so it remains persuasive yet safe. The easiest approach is to remove or replace the trigger words entirely. However, many marketers rely on phrases like “free” or “guaranteed” to capture attention. Replacing them outright can make a message feel bland or unconvincing. Instead, consider subtle variations that retain meaning but reduce the filter’s score.

  One simple trick is to insert a non‑standard character into the word. For instance, “free” becomes “free” or “free.” Spam filters look for exact matches, so a single symbol in the middle is enough to throw off the scanner. Make sure the symbol is easy for readers to read; avoid overly cryptic substitutions that might confuse your audience.

  Another strategy is to combine the word with an adjective or a context phrase that dilutes its spammy connotation. Rather than “click here,” write “tap the link below to explore.” The action verb “tap” is less common in spam and pairs naturally with “below,” creating a more conversational tone. The same principle works for “free”: “discover our complimentary guide” feels friendlier and signals a legitimate offer.

  Pay attention to the placement of these terms. Spam filters often penalize words that appear in the subject line or at the top of the email, where they are most visible. If you need a headline that draws attention, try a descriptive phrase that avoids trigger words. For example, “New insights on customer retention” instead of “Amazing tips for 99% retention.” Even a subtle change can keep the score down while still informing your readers.

  In some cases, the word itself can be replaced with a synonym that carries fewer points. “Guarantee” might become “ensured,” and “risk free” could turn into “without risk.” Test the new phrasing in a draft version to confirm it feels natural. Remember that the goal is readability, not a perfect game‑plan to dodge filters. If a substitution feels forced, consider reworking the sentence structure entirely.

  Beyond individual words, look at overall word density. A long, dense paragraph filled with promotional language will draw the filter’s attention. Break the text into shorter, digestible blocks. Use bullet lists, subheadings, and ample white space. A well‑organized email is easier for filters to parse and for readers to follow.

  Once you’ve revised the copy, run a quick test. Many free tools will highlight problematic words and suggest alternatives. Keep a checklist of the most common high‑score terms, and mark each instance before you hit “send.” This proactive approach saves time and reduces the chances of your newsletter being flagged.

  Check Before You Send: Tools & Steps

  Even the most careful writers can miss a spam trigger. That’s why testing your final draft against a spam‑score calculator is essential. A simple copy‑and‑paste tool gives you a score and a breakdown of the words that raised it. One popular free service is Lyris Content Checker, which analyzes your text using the same logic as SpamAssassin. Visit https://www.lyris.com/contentchecker, paste your email, and you’ll receive a detailed report in minutes.

  The report lists every keyword that contributed to the score and assigns a point value. Pay close attention to items that push the total above five. If your score is high, focus on those terms first. Remove, replace, or disguise them as described earlier. When you’re satisfied, run the test again to confirm the score has dropped.

  Another useful practice is to preview your email in the recipients’ inbox. Most email clients provide a preview pane that shows how the message will appear after filtering. If you notice your subject line or header landing in the spam folder in the preview, tweak it immediately.

  For ongoing quality control, schedule periodic checks as part of your publishing workflow. Treat spam testing like you would any other content review: include it in the final checklist before the mailer goes live. Over time, you’ll notice patterns - certain phrases that consistently raise the score. Update your style guide to reflect those insights, and your team will become more aware of the subtle signals that spam filters monitor.

  When you’re ready to send, consider sending a small test batch to a few colleagues or a test email address that logs spam scores. Many ISPs offer “spam score” headers in the email metadata; examine those to see how your message fares against real-world filters. This step isn’t mandatory, but it offers an extra layer of confidence.

  Finally, keep an eye on inbox analytics after you send. Most email service providers show deliverability rates, bounce rates, and spam complaints. If you notice a spike in complaints, review the content that caused the issue. Use that data to refine future issues, ensuring each new edition reaches your audience more reliably.