Do specific words instantly trigger spam filters?

No, not directly in the way they used to. Modern spam filters use machine learning algorithms that analyze hundreds of factors, not just individual words. While certain words like "free" or "guaranteed" are still associated with spam, their impact depends heavily on the overall context, your sender reputation, and how recipients interact with your emails.

What formatting choices should I avoid to prevent triggering spam filters?

It's best to avoid excessive capitalization, multiple exclamation marks, unusual fonts, and broken HTML. These formatting issues can make your email look suspicious to filters. Additionally, using too many images or having a poor image-to-text ratio can also be flagged.

What are the most important factors influencing email deliverability besides content words?

A low sender reputation is a primary reason emails go to spam. This can be caused by high bounce rates, low engagement (few opens or clicks), high unsubscribe rates, and especially high spam complaint rates. Technical issues like misconfigured SPF, DKIM, or DMARC records also significantly impact deliverability.

How can I improve my email deliverability and avoid the spam folder?

Focus on building a strong sender reputation by consistently sending valuable content to engaged subscribers. Implement and monitor email authentication protocols (SPF, DKIM, DMARC), regularly clean your email list, and encourage recipient engagement. You should also monitor your email deliverability over time.

What words and phrases are considered spammy and trigger spam filters? - Content - Email deliverability - Knowledge base

For years, email marketers have been obsessed with lists of so-called "spam trigger words." These lists often contain hundreds of terms, ranging from "free" and "guaranteed" to "act now" and "winner." The prevailing wisdom was that simply including one of these words would condemn your email to the dreaded spam folder.

The reality, however, is far more nuanced. While certain words and phrases are indeed commonly associated with unwanted emails, modern spam filters are incredibly sophisticated. They look at a vast array of factors beyond just isolated keywords.

Understanding what truly makes an email "spammy" involves a comprehensive look at sender reputation, engagement, technical authentication, and the overall context of your message. Relying solely on a blacklist (or blocklist) of words is an outdated and ineffective approach to email deliverability.

The evolution of spam filters

Spam filtering has undergone a significant transformation. In the early days, filters largely operated on simple keyword matching. If your email contained a word like "Viagra" (as was often cited in old guidelines), it was flagged as spam, regardless of context. This led to marketers trying to "trick" filters by misspelling words or adding symbols, a practice known as hashbusting, which is no longer effective.

Today, major mailbox providers like

Gmail and

Outlook employ advanced machine learning algorithms. These systems analyze vast amounts of data, learning patterns from user interactions (which emails are opened, replied to, marked as spam, or moved to promotions). They can detect suspicious behavior and content patterns far beyond a simple word list, making it difficult to pinpoint exactly why an email might land in the junk folder based on content alone. This is why many experts argue that specific spam trigger word lists are no longer relevant.

The focus has shifted from individual words to the overall context and intent of the email. A word like "free" isn't inherently spammy if used legitimately, for example, in an email about a "free webinar." However, if it's combined with other suspicious elements, such as excessive capitalization, broken authentication, or a poor sender reputation, it contributes to a higher spam score. You can read more about why keywords alone may not cause emails to be filtered.

Categories of words and phrases that raise flags

While single words are less impactful, categories of words and phrases commonly found in spam still contribute to an email's overall spam score. These categories reflect behaviors often associated with unwanted or malicious mail. It is about the combination and density of such terms, rather than a single instance.

Consider these common categories of questionable language:

Overly promotional or sales-oriented terms: Words that aggressively push for a sale or promise unrealistic gains, like "buy now," "limited time offer," "discount," "deal," or "eliminate debt."
Urgency and pressure tactics: Phrases designed to create a false sense of urgency, such as "act now," "don't miss out," "expire," or "last chance."
Financial and money-related promises: Terms promising easy wealth or significant financial benefits, for instance, "earn money," "cash," "investment," "guaranteed income," or "get rich quick."
Sensational or manipulative language: Words that are overly dramatic, unbelievable, or attempt to trick the recipient, like "miracle cure," "congratulations," "winner," "hidden," or "verify account."
Shady business or illicit content: Terms related to illegal activities, adult content, or highly regulated substances that are often abused, for instance, specific pharmaceutical names or gambling terms. We have a dedicated article on how words like "Viagra" trigger spam filters.

While these words can increase an email's spam score, their impact is greatly diminished if the sender has an excellent reputation and the email's overall context is legitimate. It's the combination of multiple red flags that truly matters.

Beyond words: other factors that trigger spam filters

Focusing solely on content words is a narrow view of email deliverability. A robust email strategy goes much deeper, addressing technical configurations and sender behavior. These factors often carry more weight than the specific vocabulary used in your email copy.

One critical aspect is email authentication. SPF, DKIM, and DMARC are fundamental protocols that verify your sending identity and help mailbox providers trust your emails. If these are not properly configured, even the most carefully crafted, spam-word-free email can land in the junk folder or be rejected outright. You can learn more in our guide on DMARC, SPF, and DKIM.

Sender reputation, both for your sending IP address and domain, is another paramount factor. This reputation is built over time based on your sending history, complaint rates, bounce rates, and whether your emails are consistently opened and engaged with by recipients. A poor reputation can lead to your emails being marked as spam or even added to a blocklist (or blacklist). We have a comprehensive guide on how email blacklists actually work. Other contributing elements include the overall design and formatting of your email, the use of excessive punctuation or all caps, and the presence of suspicious links or attachments. Mailchimp provides further insights into how to avoid spam filters.

Best practices for avoiding the spam folder

To ensure your emails reach the inbox, adopt a holistic approach to deliverability. This means moving beyond a simple word list and focusing on building a trustworthy sending infrastructure and maintaining positive recipient engagement. The path to good inbox placement is multifaceted.

Maintain a clean email list: Regularly remove inactive or unengaged subscribers, and use double opt-in to ensure subscribers genuinely want your emails. This helps reduce bounce rates and spam complaints.
Personalize and segment: Tailor your content to specific segments of your audience. Relevant content is more likely to be opened and engaged with, which positively impacts your sender reputation.
Prioritize email authentication: Implement and monitor SPF, DKIM, and DMARC. These protocols are crucial for verifying your identity and preventing spoofing. Our article on how to avoid spam filters effectively covers more on this.
Monitor your deliverability metrics: Keep an eye on your open rates, click-through rates, unsubscribe rates, and spam complaint rates. These metrics provide valuable insights into your sender reputation and audience engagement.

By focusing on these foundational elements, you'll naturally create emails that are less likely to trigger spam filters, regardless of the occasional "free" or "offer" in your content. It's about building trust with both your recipients and mailbox providers.

Views from the trenches

Best practices

Always prioritize sender reputation over individual word choices in your emails.

Implement strong email authentication (SPF, DKIM, DMARC) for all sending domains.

Segment your audience and personalize content to increase engagement rates.

Regularly clean your email lists to remove inactive or bouncing addresses.

Common pitfalls

Over-reliance on outdated spam word lists can lead to ineffective email strategies.

Using excessive capitalization, exclamation marks, or suspicious formatting.

Ignoring technical email authentication, which is a major red flag for filters.

Sending to unengaged or purchased lists, leading to high complaint rates.

Expert tips

Modern spam filters use machine learning, so context and behavior matter most.

Even small providers use rules that can flag numbers or specific phrases.

If an email is landing in spam, look beyond content to technical factors and engagement.

The overall 'spamminess' of an email is a cumulative score, not just one word.

Marketer view

Marketer from Email Geeks says they often encounter frustratingly outdated advice from reputable ESPs, like the idea that simple words such as "free" or "guaranteed" are instant spam triggers.

2024-09-11 - Email Geeks

Marketer view

Marketer from Email Geeks says they think many of these outdated articles might be generated by AI without proper fact-checking or are simply very old and haven't been updated.

2024-09-12 - Email Geeks

Prioritizing true deliverability

While knowing about potentially "spammy" words and phrases can offer some guidance, it's crucial to understand that modern email deliverability is far more complex than simple keyword avoidance. The key to successful inbox placement lies in a strong sender reputation, proper technical authentication, and consistent engagement from your recipients.