Spam Filter Words: What Makes Emails Look Spammy?

Spam Filter Words: What Makes Emails Look Spammy?

You’ve crafted the perfect email campaign. Your subject line is compelling, your message is clear, and your call-to-action is strong. 

But three days later, you check your campaign stats and see a disappointing 2% open rate.

What happened? 

According to Return Path’s 2024 Deliverability Benchmark Report, 16% of legitimate marketing emails never reach the inbox, with spam filter triggers being the leading cause. 

For sales teams relying on email outreach, this means nearly 1 in 6 carefully crafted messages disappear before prospects even know they exist.

Once you understand which words trigger spam filters and why, you can write emails that reach your prospects’ inboxes instead of disappearing into digital purgatory. 

In this guide, I’ll show you exactly which words and phrases make emails look spammy, and give you practical strategies your team can implement immediately to keep the emails out of the spam folder.

What are spam filters and how do they work?

Spam filters act as barriers, protecting inboxes from unwanted emails. These algorithms evaluate every incoming email and decide whether it belongs in the inbox or should be flagged as spam.

Source

According to Statista, spam emails account for approximately 45% of all email traffic worldwide, that’s billions of junk messages daily.

ithout effective spam filters, inboxes would be flooded and practically unusable.

How do spam filters evaluate your emails?

Modern spam filters don’t rely on just one signal. They analyze multiple factors simultaneously to determine whether your email is legitimate or spam:

1️⃣ Content Analysis

Spam filters scan your email’s text, subject lines, formatting, and links. They look for:

• Common spam trigger words
  
• Excessive capitalization
  
• Suspicious or broken link structures
  These patterns are red flags that can cause emails to be filtered out.

2️⃣ Sender reputation

Your sending history plays a major role. Filters track:

• How consistently do you follow best practices
  
• Whether recipients engage with your emails
  
• Past spam complaints
   

Insight from Chad White, Research Director at Oracle Marketing Consulting:

“Modern spam filters don’t just count trigger words, they analyze context, sender behavior, and recipient engagement patterns. The most effective approach is building genuine relationships rather than trying to outsmart the algorithms.”

3️⃣ Engagement tracking

Spam filters monitor how recipients interact with your emails:

• High open and click-through rates = stronger sender score
  
• Frequent spam complaints or low engagement = damage to your sender reputation (sometimes for months)

4️⃣ Machine learning and adaptation

Today’s spam filters use machine learning to stay ahead of evolving spam tactics.

They process millions of emails daily, identifying new patterns and updating their algorithms. What worked in your campaigns last year may no longer pass the filter today.

Common spammy words and phrases in emails that trigger spam filters

According to Validity’s 2024 Sender Score Benchmark Report, emails containing 3 or more promotional trigger words are 67% more likely to be filtered as spam compared to those using neutral language. 

Here are the main categories that consistently cause problems:

Do promotional words really send emails to spam?

Yes, but it’s about patterns, not just individual words.

👉 Emails with 3 or more promotional trigger words are 67% more likely to land in spam.

👉 A single trigger word, used in the right context, rarely causes issues.

Spam filters flag these words because scammers have overused them for decades to create fake urgency and mislead recipients. 

Unfortunately, even legitimate businesses can get caught in the crossfire.

Common categories of spam trigger words

1️⃣ Promotional words that raise red flags

Terms like “free,” “buy now,” or “discount” are spam filter magnets because of their long association with shady offers.

Examples of promotional triggers:

• Free
• No cost
• Buy now
• Purchase
• Order now
• Discount
• Sale
• Special promotion
• Limited offer
• Clearance
• Deal

Tip: Instead of: “Free consultation – act now!”

Try: “Complimentary strategy session to discuss your goals.”

2️⃣ Urgency language that backfires

Filters are wary of words that create artificial pressure, a favorite tactic of scammers pushing fake deadlines.

Examples of urgency triggers:

• Urgent
• Emergency
• Act now
• Don’t wait
• Last chance
• Expires
• Hurry
• Rush
• Immediate
• Time sensitive
• Don’t miss out
• Final notice

Tip: Instead of: “Urgent, your account will be suspended”

Try: “Action needed: Please update your account information by Friday.”

3️⃣ Financial & get-rich-quick phrases

Anything that promises easy money or guaranteed income puts your email at risk of being filtered.

Examples of financial triggers:

• Make money
• Earn cash
• Financial freedom
• Get rich
• Cash bonus
• Guaranteed income
• Easy money
• Profit
• Investment opportunity
• Million dollars
• Credit check

Tip:

Instead of: “Make money fast with our investment program”
Try: “Learn about our investment options and potential returns.”

4️⃣ Overused marketing jargon

These phrases have been spammed into oblivion. They signal low trust to spam filters.

Examples of marketing triggers:

• Risk-free
• 100% guaranteed
• Satisfaction guaranteed
• No obligation
• Money back
• Exclusive
• Secret
• Fantastic
• Revolutionary
• Incredible
  

5️⃣ Suspicious & Phishing-Related Terms

These words are heavily associated with scams, illegal activities, or phishing attempts.

Examples of suspicious triggers:

• Viagra
• Pills
• Weight loss
• Miracle
• Cure
• Medicine
• Password
• Verify
• Confirm
• Winner
• Congratulations
• You’ve been selected
• Claim now

It’s not about avoiding these words entirely; it’s about using them thoughtfully, in the right context, and within high-quality, well-structured emails.

Focus on clear, honest communication that builds trust; that’s the best way to stay out of the spam folder.

Check the complete list of spam-triggering keywords. 

Why do these words trigger spam filters?

Understanding why spam filters flag certain words is key to writing better emails and protecting your sender’s reputation.

1️⃣ Historical patterns shape filter decisions

Spam filters learn from experience. When millions of scam emails contain phrases like “make money fast”, the system recognizes a pattern.

It’s not that these words are inherently bad; it’s that scammers have poisoned them through overuse.

2️⃣ Context matters more than any single word

A single trigger word won’t automatically land your email in spam.

What filters really watch for is the overall pattern:

• Multiple promotional terms
• Excessive exclamation points
• Poor grammar
• Spammy email formatting

One promotional word used appropriately? Fine.

An email loaded with spammy signals? Risky.

3️⃣ Filters analyze your writing style

It’s not just about what you say, it’s how you say it.

Filters flag emails with:

• ALL CAPS text
• Multiple exclamation marks
• Bright red fonts
• Strange or inconsistent formatting

These are typical tactics spammers use to grab attention, and filters are trained to spot them.

4️⃣ User reports feed spam databases

Every time a recipient marks an email as spam, that message helps train the system.

Spam filters analyze these reported emails to:

• Identify common phrases
• Build new trigger rules
• Refine their detection patterns
  

5️⃣ Machine learning keeps filters evolving

Today’s spam filters don’t just follow fixed rules.

They’re powered by machine learning, constantly adapting to new scam tactics and adjusting their trigger criteria.

The list of risky words and patterns evolves as filters get smarter.

The underlying principle is simple: If something looks, sounds, or behaves like spam, it probably gets treated like spam even if that wasn’t your intention.

How can I avoid spammy words to prevent my emails from going to spam?

Avoiding spam trigger words can , help you reach more prospects. 

Write naturally, like you’re talking to a colleague, not selling hard. 

Replace terms like “free” with “complimentary,” “urgent” with “time-sensitive,” and focus on specific value rather than vague promises. 

Trigger Word	Professional Alternative	Why It Works Better
Free	Complimentary, included	Less promotional, more professional
Guaranteed	Typically, often results in	More honest, builds trust
Urgent	Time-sensitive, important	Conveys priority without pressure
Act now	Please respond by [date]	Specific and respectful
Deal	Opportunity, option	Professional and consultative

Before sending, test your emails using tools like Mail Tester, and track engagement to protect your sender reputation. 

Building trust through clear, genuine communication is the best way to stay out of spam folders.

Read more about avoiding spam filters from our article on “How to avoid spammy words?”

Increase your email deliverability with SmartReach.io

Many of these deliverability challenges can be addressed through the right toolset and monitoring approach. 

SmartReach’s email deliverability suite is specifically designed to tackle the most common causes of spam folder placement.

SmartReach.io offers built-in AI-based email warm-up service WarmupHero that warms up your email inboxes naturally improving the sender reputation and overall email deliverability. 

The system monitors important metrics like how many warmup emails end up in the inbox versus spam folders, keeping constant watch on your email health.

Also, there is Inbox rotation feature that auto distributes your sending emails across multiple verified email addresses within your campaign. 

By rotating inboxes, you avoid triggering spam filters that flag high-sending volumes from single addresses, maintaining a healthy sender reputation and ensuring better inbox placement.

ESP matching technology intelligently pairs your email sending with your recipient’s email service provider. 

When emails arrive from matching ESPs (like sending Gmail emails through Gmail’s servers), it raises fewer red flags for spam filters and builds consistent sending patterns that boost deliverability.

To protect your reputation further, SmartReach includes unlimited free email validation, which ensures your campaigns only target valid email addresses. 

Spam testing adds another layer of protection by running automated checks on your account setup and campaign. It verifies SPF, DKIM, and DMARC records and global backlinks status for your domain. 

Remember, the goal isn’t to trick spam filters, it’s to write better emails that recipients actually want to receive. 

When you focus on providing genuine value and building real relationships, combined with proper technical infrastructure, deliverability problems often solve themselves.

Try SmartReach.io free for 14 days. 

Conclusion

Spam filters are designed to block unwanted emails, but careless word choices or aggressive language can cause even legitimate messages to land in spam. 

The real solution isn’t trying to outsmart these filters; it’s writing better emails. Focus on genuine value, natural language, and building real relationships. Small changes, like replacing trigger words with conversational alternatives, can dramatically improve deliverability and engagement.

For sales leaders, setting clear content guidelines, tracking deliverability, and using the right tools can protect your sender reputation and achieve massive ROI. At the end of the day, if you write emails you’d want to receive, spam filters will take care of themselves.

Frequently asked questions

What percentage of emails go to spam due to trigger words?

According to Validity’s 2024 Sender Score Benchmark Report, emails containing three or more promotional trigger words are 67% more likely to be filtered as spam compared to those using neutral language. However, single trigger words rarely cause deliverability issues when used in proper context.

How many spam trigger words will send my email to spam?

There’s no magic number, but emails with 3+ promotional trigger words face significantly higher spam filter risk. Context matters more than count—an email with multiple trigger words, poor grammar, and excessive formatting is much more likely to be flagged than one with a single promotional word used appropriately.

Can I use words like “free” and “guaranteed” in business emails?

Yes, but use them strategically. Replace “free” with “complimentary” or “included” and “guaranteed” with “typically results in” or “often achieves.” The goal is to maintain professionalism while avoiding overused spam language.

How do I know if my emails are going to spam folders?

Monitor your campaign metrics closely. Low open rates (under 15% for cold outreach), poor click-through rates, and high bounce rates often indicate deliverability issues. Tools like SmartReach’s Deliver4Sure provide comprehensive deliverability monitoring and inbox placement tracking.

What’s the difference between email delivery and email deliverability?

Email delivery means your email was accepted by the recipient’s server, it doesn’t guarantee inbox placement. Email deliverability measures whether emails reach the primary inbox where recipients actually see them. You can have 95% delivery, but poor deliverability if most emails land in spam.

How long does it take to improve email deliverability?

With proper implementation of best practices, most businesses see improvement within 30-60 days. However, severely damaged sender reputations may take 3-6 months to fully recover. Starting with email warming and gradually increasing volume while monitoring metrics typically shows results within the first month.

Should I avoid all promotional language in sales emails?

No, but be strategic about it. Use natural, conversational alternatives to trigger words. Instead of “This incredible opportunity will transform your business,” try “I’d like to share an approach that’s helped similar companies improve their results.” Focus on specific value rather than vague promises.

How does inbox rotation help with deliverability?

Inbox rotation distributes your email sending across multiple verified email addresses, preventing any single address from appearing to send high volumes. This mimics natural sending patterns and reduces the risk of triggering spam filters that flag bulk sending from individual accounts.