Are email spam trigger words still relevant for deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 10 Aug 2025
Updated 19 Aug 2025
7 min read
The question of whether email spam trigger words still play a significant role in deliverability is a common one. Years ago, the answer was a clear yes. Email filters were simpler, relying heavily on keyword matching to flag suspicious messages. Terms like "free," "guarantee," or "money back" were almost guaranteed to land your email in the junk folder, regardless of your sender's intent.
However, email filtering technology has evolved dramatically. Modern spam filters are far more sophisticated, employing advanced algorithms, machine learning, and artificial intelligence to assess emails. This shift has led many to believe that the concept of a "spam trigger word list" is now obsolete. So, what's the truth? Are these words still a deliverability concern, or can we send emails without worrying about a specific vocabulary?
The evolution of spam filtering
In the early days of email, spam filters were quite basic. They functioned much like a simple content scanner, looking for predefined keywords and phrases commonly associated with unsolicited bulk email (spam). If your email contained enough of these flagged terms, it would be assigned a "spam score" that likely pushed it into the junk folder.
This led to the widespread belief in rigid spam trigger word lists, which marketers meticulously avoided. However, spammers quickly adapted, finding ways to bypass these simple rules. In response, inbox providers (ISPs) like Gmail and Outlook realized that a more dynamic and contextual approach was needed to accurately identify spam.
Today's spam filters evaluate hundreds, if not thousands, of signals beyond just keywords. These signals include sender reputation, email authentication (SPF, DKIM, DMARC), engagement metrics (opens, clicks, replies), complaint rates, bounce rates, and even the overall formatting and link structure of the email. A single word, even one historically considered a "trigger," is highly unlikely to be the sole reason an email lands in spam, especially if your other deliverability factors are strong.
Why sender reputation is paramount
The shift in focus has been profound: sender reputation is now the single most critical factor determining inbox placement. Your domain and IP's reputation, built over time through consistent sending practices and positive recipient engagement, outweighs the impact of individual words in your email content. A strong sender reputation signals to ISPs that you are a legitimate sender sending desired mail.
This means that even if you use a word that was once on a common spam list, if your overall sending behavior is good, recipients are engaging positively with your emails, and your authentication records are correctly configured, you are much more likely to reach the inbox. Conversely, even emails with pristine, "non-spammy" content will go to spam if your sender reputation is poor.
Mailjet, a prominent email service provider, highlights that phrases and practices, not just isolated words, are what to avoid. This aligns with the understanding that context and overall sending patterns are more influential than individual keywords. You can learn more about why emails go to spam in our detailed guide.
The key takeaway is that content is a component of your overall deliverability, but not typically the sole deciding factor it once was. Its impact is more indirect, influencing how recipients interact with your emails, which in turn affects your sender reputation. Positive engagement improves your reputation, while negative actions like spam complaints or disengagement will damage it.
Old filtering focus
Historically, spam filters operated on static, predefined lists of keywords and phrases. The presence of a certain number of these spammy words would significantly increase an email's spam score, often leading to immediate junk folder placement. This method was simple but easy for spammers to circumvent by simply rephrasing their messages.
Sender reputation was less emphasized, and the focus was primarily on content inspection. If your content contained enough problematic terms, it didn't matter if you were a legitimate sender or not.
Modern filtering focus
Today's advanced filters use sophisticated machine learning models that analyze a wide array of signals. While content is still considered, it's assessed within the context of overall sending behavior and recipient engagement. The primary determinant of inbox placement is now your sender reputation.
Engagement metrics (opens, clicks, replies, deletes without opening) heavily influence this reputation. Reputable industry experts emphasize that reputation is more important than specific words. An email containing "trigger words" from a highly reputable sender with strong engagement is less likely to be flagged than a benign email from a sender with a poor reputation.
Content's nuanced role
While isolated spam trigger words have diminished in direct impact, their relevance is not entirely zero. The context in which words are used still matters. For example, a single mention of "free" in an otherwise legitimate email is unlikely to be problematic. However, an email packed with aggressive, sales-oriented language, excessive capitalization, multiple exclamation points, and a high concentration of historically spammy terms might still raise flags.
This is especially true for smaller, less sophisticated mail servers or those with older spam filtering systems (like some SpamAssassin installs). These systems might still rely more heavily on keyword matching and heuristic rules. While most major ISPs have moved beyond this, it's a factor to consider if your audience includes recipients on diverse email platforms. The question of do specific email keywords trigger spam filters is more about context and combination than individual words.
Ultimately, the best approach is to focus on writing clear, concise, and valuable content that resonates with your audience. Avoid manipulative or overly promotional language that might feel spammy to a human reader, as this can lead to negative engagement signals. For example, while the word "free" can impact deliverability, it's often due to the broader context of the message and not just the word itself.
Content best practices
To ensure your content aids deliverability rather than hinders it, consider these best practices:
Audience focus: Craft emails that genuinely provide value and are relevant to your subscribers. This naturally leads to better engagement.
Clear language: Avoid hyperbolic or sensational language that spammers often use. Be direct and transparent.
Balanced content: While some promotional words are necessary, use them in moderation. Avoid patterns that mimic classic spam, such as all caps or excessive exclamation marks.
Test and monitor: Pay attention to your deliverability rates and engagement metrics. If you see dips, investigate other factors before solely blaming content.
A holistic deliverability approach
Beyond content, a robust email deliverability strategy encompasses several technical and behavioral elements that significantly outweigh the impact of individual words. Ensuring these foundational elements are in place is far more crucial than obsessing over a spam word list.
Email authentication is paramount. This includes setting up and maintaining strong SPF, DKIM, and DMARC records. These protocols verify that your emails are legitimately from your domain and haven't been tampered with. Without proper authentication, even the most perfectly worded email can be rejected or flagged as spam. The example DMARC record below demonstrates a common setup.
List hygiene is another critical factor. Sending to invalid or disengaged email addresses can lead to high bounce rates and spam trap hits, which severely damage your sender reputation. Regularly cleaning your email lists and removing inactive subscribers helps maintain a healthy sending environment.
Finally, consistent monitoring of your deliverability metrics is essential. This includes tracking your open rates, click-through rates, unsubscribe rates, and spam complaint rates. Tools like blocklist checkers can also alert you if your IP or domain gets listed on a major blacklist (or blocklist), which would indicate a serious deliverability issue unrelated to specific content words. The more you understand these factors, the better equipped you'll be.
Views from the trenches
Best practices
Focus on building and maintaining a strong sender reputation through consistent positive engagement from recipients.
Prioritize proper email authentication (SPF, DKIM, DMARC) to verify your sender identity.
Regularly clean your email lists to remove inactive or invalid addresses, reducing bounces and spam trap hits.
Craft valuable, relevant, and engaging content that encourages positive recipient interactions.
Monitor your deliverability metrics, including open rates, click-through rates, and complaint rates.
Common pitfalls
Over-relying on outdated spam trigger word lists and neglecting modern filtering complexities.
Sending to unengaged or purchased lists, leading to high bounce rates and spam complaints.
Failing to implement or properly configure email authentication protocols like SPF, DKIM, and DMARC.
Ignoring negative engagement signals, such as low open rates or high spam complaint rates.
Sending inconsistent email volumes, which can appear suspicious to ISPs.
Expert tips
Modern spam filters prioritize sender reputation and engagement over isolated content keywords.
While specific words are less impactful, the overall context and tone of your email can still influence deliverability.
Even if your emails have 'spammy' words, a strong sender reputation built on positive engagement can often override them.
Focus on user behavior: if your emails drive spam complaints or are consistently ignored, your deliverability will suffer regardless of content.
Some niche or older email systems might still rely more on traditional keyword filtering, but major ISPs do not.
Expert view
Expert from Email Geeks says most deliverability professionals emphasize that sender reputation is far more crucial than the specific words used in an email.
2019-09-24 - Email Geeks
Expert view
Expert from Email Geeks says that older, content-based spam filters relying on keyword matching were early iterations that were only useful for a brief period. The evolution of filtering has made them largely redundant.
2019-09-24 - Email Geeks
The path to better deliverability
The idea of email spam trigger words as an absolute blocklist (or blacklist) that guarantees spam folder placement is largely a relic of the past. Modern email deliverability is a complex ecosystem where sender reputation, email authentication, and recipient engagement are the dominant factors. While it's wise to avoid excessively aggressive or deceptive language, a holistic approach to email deliverability will yield far better results.
Focus on building a trustworthy sender identity, maintaining clean lists, sending relevant and engaging content, and monitoring your performance. By prioritizing these elements, you can ensure your emails consistently reach the inbox, where your messages can truly connect with your audience.
Gmail and 
Outlook realized that a more dynamic and contextual approach was needed to accurately identify spam.
