Do spam trigger words affect email deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 2 Aug 2025
Updated 18 Aug 2025
6 min read
It is a common belief that certain "spam trigger words" will automatically send your emails straight to the junk folder. This idea has been around for years, leading many marketers and senders to meticulously curate their content, avoiding words like "free," "winner," or "guarantee" at all costs. The truth is, the landscape of email deliverability has evolved significantly, making this notion largely outdated.
While specific keywords once played a more prominent role in basic spam filtering, modern spam filters, powered by advanced artificial intelligence and machine learning, analyze a much broader range of factors. They are far more sophisticated than simple word scanners, focusing instead on overall sender reputation, engagement, and behavioral patterns.
The evolution of spam filtering
Today's email filtering systems are highly intelligent. They learn from vast amounts of data, identifying patterns of legitimate email versus spam. This means that a single word, even one historically associated with spam, is unlikely to be the sole determinant of whether your email reaches the inbox. Context, sender history, and recipient engagement now carry far more weight.
Consider a transactional email from a reputable bank that includes the word "fraud alert." If simple keyword filtering were still the primary mechanism, this crucial message might land in spam, despite its legitimate purpose and high sender reputation. This highlights how filters prioritize the sender's established trust and the email's overall intent over individual word choices.
What truly matters is the overall picture of your sending practices. Are your recipients expecting your emails? Do they open, click, and reply to your messages? Or do they mark them as spam, delete them unread, or ignore them consistently? These engagement signals, combined with proper email authentication like SPF, DKIM, and DMARC, are what really drive inbox placement.
Misconceptions and outdated advice
Despite the advancements in spam filtering technology, the myth of the "spam trigger word list" persists. You'll still find numerous articles and guides online featuring extensive lists of words to avoid. This outdated advice often misleads senders, causing them to focus on minor content tweaks instead of addressing fundamental deliverability issues.
Many of these lists originate from a time when spam filters were far less sophisticated. They were simple rule-based systems that would assign a "spam score" based on keywords, all caps, excessive punctuation, and other easily identifiable characteristics of unsolicited mail. While some basic patterns like all caps in subject lines can still be a minor flag, the reliance on specific words is largely obsolete.
The real problem
The danger in obsessing over these lists is that it distracts from what truly impacts email deliverability. Improving your inbox placement requires a holistic approach that focuses on maintaining a healthy sender reputation, building an engaged audience, and ensuring your technical configurations are sound. Concentrating solely on word choices is akin to bailing out a leaky boat with a teacup while ignoring the gaping hole in the hull.
The real drivers of email deliverability
So, if spam trigger words aren't the main issue, what is? Modern email deliverability hinges on a combination of factors, with sender reputation being paramount. Your reputation is like a credit score for your email sending, built up over time through consistent positive engagement from your recipients and adherence to best practices. A strong reputation signals to internet service providers (ISPs) that your mail is legitimate and desired.
Engagement metrics play a crucial role in shaping this reputation. When recipients consistently open your emails, click on links, and move them from spam to inbox, it sends a powerful positive signal to ISPs. Conversely, low open rates, high bounce rates, spam complaints, and emails being deleted without being read will negatively impact your sender reputation, regardless of the words you use. Mailchimp also emphasizes the importance of content quality in avoiding spam filters.
Technical compliance, including email authentication protocols, is another critical component. Protocols like SPF, DKIM, and DMARC verify that your emails are legitimately coming from your domain and haven't been tampered with. Without proper authentication, even mail from a good sender reputation can be flagged. You can learn more about these foundational elements in our guide to understanding DMARC, SPF, and DKIM.
Outdated approach
Focus: Strictly avoiding a specific list of "spam trigger words" in subject lines and body copy, like "free" or "win big".
Assumption: Keyword detection is the primary spam filter mechanism.
Outcome: Limited improvement in deliverability, potential for legitimate emails to be flagged due to context, and a false sense of security.
Modern approach
Focus: Building strong sender reputation, ensuring recipient consent, optimizing engagement, and implementing robust email authentication.
Assumption: AI and machine learning analyze a wide array of factors, prioritizing behavioral signals and authentication.
Outcome: Significantly improved inbox placement, higher engagement rates, and protection against impersonation and phishing.
Ultimately, context is king. A word like "free" in an email from a trusted e-commerce brand announcing a free shipping offer is unlikely to trigger spam filters if that brand has a strong sending history and engaged subscribers. However, the same word in an unsolicited email from a new, unauthenticated sender with suspicious content could easily land in the junk folder. HubSpot also highlights that avoiding certain words doesn't guarantee inbox delivery.
Strategies for better inbox placement
Instead of fixating on individual words, shift your focus to a comprehensive deliverability strategy. This involves building and maintaining a positive sender reputation through consistent, valuable email campaigns. Start by ensuring you have explicit consent from all recipients before sending them emails. This foundation of consent helps prevent spam complaints, which are a major red flag for ISPs.
Regularly monitor your engagement metrics. Track your open rates, click-through rates, and bounce rates. A high bounce rate indicates issues with your recipient list, which can harm your sender reputation. Cleaning your email list regularly to remove inactive or invalid addresses is a vital step in maintaining good health. You can also monitor your blocklist (or blacklist) status using a blocklist checker.
Implement and maintain strong email authentication. Properly configured SPF, DKIM, and DMARC records are non-negotiable for modern email sending. These technical safeguards help ISPs verify your identity and protect your domain from impersonation (phishing). If you're encountering issues, refer to our guide on how to fix DMARC issues in Microsoft 365 and Google Workspace.
By focusing on these core principles, you'll see a significant improvement in your email deliverability, ensuring your messages reach the intended recipients and achieve your communication goals.
Views from the trenches
Best practices
Always prioritize recipient consent and build a clean, engaged email list to improve deliverability.
Focus on sender reputation and engagement metrics, as these are primary factors for ISPs.
Properly configure email authentication protocols such as SPF, DKIM, and DMARC for legitimacy.
Regularly clean your email lists to remove inactive or invalid addresses, reducing bounce rates.
Understand that context matters more than individual words in modern spam filtering algorithms.
Common pitfalls
Over-reliance on outdated "spam trigger word" lists, which distracts from core deliverability issues.
Ignoring sender reputation and engagement signals, leading to poor inbox placement despite content efforts.
Believing that simply avoiding certain words guarantees emails will bypass spam filters.
Using deceptive or overly promotional language that can still accumulate negative signals from recipients.
Failing to implement or monitor email authentication, making your emails appear untrustworthy to ISPs.
Expert tips
If a legitimate email containing a "spammy" word still lands in spam, the issue is likely deeper than content alone.
Focus on providing real value to your audience to foster positive engagement.
Test your emails with an email deliverability tester to identify potential issues beyond content.
Educate your users about modern spam filtering to counter outdated beliefs.
Monitor your domain reputation closely through tools like Google Postmaster Tools.
Marketer view
Marketer from Email Geeks says that any word or phrase in any language can become a spam trigger word, because spam filters primarily assess content similarity to previously flagged messages. Deliverability hinges on consent, not just content.
2025-07-27 - Email Geeks
Marketer view
Marketer from Email Geeks says that sending an email with every
2025-07-27 - Email Geeks
Key takeaways for modern email sending
The idea that specific "spam trigger words" will automatically doom your emails to the spam folder is a relic of the past. While poor content choices can contribute to a negative overall signal, modern spam filters are far too sophisticated to rely solely on keyword matching. Focus on building and maintaining a strong sender reputation, ensuring recipient consent, optimizing engagement, and implementing robust email authentication. These are the true pillars of successful email deliverability in today's digital landscape.
Microsoft 365 and 
Google Workspace.
