Beyond Email Spam Filters: Words to Use and Avoid for Better Email Deliverability 

Getting emails into inboxes is harder than you think. Email spam filters are on high alert, flagging not just shady senders but even legitimate emails with the wrong language. 

Words that seem innocent—like “free” or “act now”—can trigger filters that stop messages before they’re even seen. This isn’t just a tech issue; it’s a business problem. Every missed email is a missed opportunity to connect, convert, and build trust with your audience.

Understanding which words to use and which words to avoid can make the difference between hitting the inbox and landing in the spam folder. In this guide, we’ll get into practical language choices that improve email deliverability and avoid spam traps so your messages end up where they should be: in front of your readers.

Understanding Email Spam Filters

Email spam filters assess emails by looking for patterns and words that are common in spam messages. They use algorithms to evaluate the sender’s reputation, subject lines, and email content.

If an email looks suspicious, it can be blocked, or worse, the sender could be penalized, and their future deliverability rates will suffer. Avoiding certain “trigger” words, like “act now” or “guaranteed results,” helps with inbox placement so your message gets to real people.

What is Email Deliverability?

Email deliverability is the ability of an email to reach the recipient’s inbox rather than getting filtered out or placed in the spam folder. This is essential for ensuring that marketing messages, updates, or communications are seen.

Email deliverability is affected by the following:

• Sender Reputation: Built on the sender’s history and domain IP, influencing how email providers treat emails from that source.

• Content Quality: Emails with spam-triggering words or excessive promotional are more likely to be flagged

• Authentication: Using SPF, DKIM, and DMARC helps verify the sender’s identity.

• Engagement Rates: High engagement, like opens and clicks, signals to providers that emails are relevant to recipients, improving deliverability.

What Are Spam Trigger Words?

Certain words and phrases can cause spam filters to block your email. Knowing what these spam “trigger” words help improve visibility and avoid common mistakes with email spam words.

Words like “free,” “winner,” and “urgent” are often linked to spam or phishing. While they’re not always a problem, overusing them or pairing them with other red-flag language increases the risk of getting filtered out.

Exaggerated claims or urgent calls-to-action (CTA) can trigger spam filters, which tend to block emails that promise unrealistic outcomes. Language that sounds too good to be true, like “guaranteed success” or “exclusive deal,” is often flagged. Keeping language realistic and simple helps your emails not get marked as spam.

Why Certain Words Get Flagged By Spam Filters

Spam filters don’t just pick words at random; there’s logic behind it.

Spam filters flag specific words for various reasons that relate to both technical and psychological principles:

• Unrealistic or Unsubstantiated Promises: Words that imply outcomes that can’t be guaranteed, like “instant” or “guaranteed,” can mislead recipients, lowering trust in the content.

• Exaggerated or Sensational Language: Filters detect words associated with hype or over-promising, as they often signal manipulative content.

• Pushy and Manipulative Language: Terms that pressure or manipulate, such as “must act now,” are flagged because they prioritize urgency over informed decision-making and tap into psychological triggers like scarcity or fear of missing out (FOMO).

• Appeals to Greed or Fear: Words that exploit emotional triggers, like greed (“make money fast”) or fear of loss, are considered intrusive by spam filters, which aim to protect users from high-stakes, impulsive appeals.

• Association with Common Spam or Scams: Many flagged words are commonly used in known spam or phishing scams, so filters associate them with harm.

• Too Much Sales or Commercial Language: Language that’s too focused on sales, discounts, or incentives can seem too commercial, triggering filters that prioritize user protection over marketing.

Psychologically, filters recognize that emails with aggressive language or appeals to greed or fear seem less trustworthy. They aim to protect users from manipulative content. On the other hand, emails with clear, informative language are more likely to get through filters and appear relevant to the recipient.

Common Spam Trigger Words

Knowing which words can trigger spam filters is key to good email deliverability. Now that you know why certain words get flagged, you can craft your messaging to get to your audience’s inbox.

Financial and Monetary Triggers 

Words related to financial incentives can be seen as spam because of their association with phishing or scams. These words imply promises of extra cash or deals that many spam emails make to lure recipients. Use clear, factual language to avoid these filters.

Urgency and Scarcity Triggers 

Creating urgency can work, but words that feel too pushy or desperate get flagged by spam filters. Use a neutral tone to convey timeliness without triggering filters.

Marketing and Advertising Triggers 

Spam filters flag some marketing language, especially when it sounds too promotional. Subtle language can often have the same effect without getting flagged.

Over-Promising Phrases

Exaggerated language makes emails sound like spam, especially when they promise unrealistic results. Use clear and honest language to improve credibility and deliverability.

Sales and Promotional Language

Standard sales jargon, when overused, often causes emails to be labeled as spam. Use language that conveys value without sounding promotional to avoid this.

Health and Medical Claims

Emails that contain health-related promises, especially around weight loss or treatments, get flagged as spam. Use straightforward and realistic language to talk about health topics without triggering filters.

Legal and Loan Language

Legal and financial language gets flagged as spam due to associations with debt consolidation and other sensitive topics. Use precise language to communicate without getting caught in spam filters.

Technology and IT-Related Terms

Technology and data-related phrases can often look like phishing attempts to spam filters, especially when talking about data collection or system access. Use less intrusive language to maintain clarity without triggering filters.

Commonly Abused Words

Frequent use of certain words in emails, especially regarding offers or opportunities, gets flagged as spam by filters. Use precise, descriptive language to keep your marketing emails more visible and engaging.

Miscellaneous Terms

Certain generic phrases often raise red flags in spam filters, particularly if they sound too promotional or vague. Choose a specific and direct language to make your emails look genuine and bypass spam filters.

Spam Triggers to Avoid in Email Subject Lines

The subject line is one of the most scrutinized parts of an email. Certain words and formatting can instantly flag your message as spam, reducing its reach.

Subject lines with promotional language or over-promises get flagged, as these are typical of unsolicited or low-value emails. Use straightforward and honest language to prevent this and get to your readers.

How to Write Emails that Bypass Spam Filters

Writing emails that get past spam filters requires a balance of clear and informative language and a respectful tone. Here’s what to do:

• Use a Professional Tone: Be professional yet conversational. Avoid using too casual language and excessive exclamations.

• Use Clear, Honest Language: Provide clear information on what the reader can expect without making promises. Honesty builds trust and reduces spam filter triggers.

• Include a Clear Call to Action (CTA): Make your CTA direct but not urgent. Phrases like “Explore options” instead of “Buy now” are less likely to trigger filters.

• Balance Visuals and Text: Maintain a 60-40 ratio of text to images. Emails that are too image-heavy can trigger spam filters. Make sure each image has alt text for accessibility.

• Ask Subscribers to Whitelist Your Email Address: Trust from subscribers improves deliverability and gets past spam filters.

• Avoid Trigger Words in Groups: Don’t group multiple high-risk spam words (e.g., “free,” “guarantee,” “winner”) in one sentence. This combination significantly raises the chances of the email being flagged. Use them sparingly and individually.

• Don’t Overuse Capital Letters or Punctuation: Excessive use of ALL CAPS or exclamation points (!!!) looks spammy and can trigger filters. Use punctuation and capitalization properly to maintain readability and professionalism.

• Avoid Repetition and Misleading Claims: Repeating the same points or using phrases that imply urgency or scarcity too often can be spammy. Focus on factual statements to help the reader understand the true value of the content.

• Limit Links and Ensure They’re Secure: Too many links, or links to non-secure sites, can make an email appear spammy. Stick to a few relevant links with HTTPS-enabled URLs.

• Avoid Overly Promotional Language: Words like “guaranteed,” “best price,” and “double your money” get emails flagged. Focus on real value, not promotional language.

• Add Recipient’s Name and Relevant Details: Including the recipient’s name or specific details (like location) makes the email feel personalized, reducing spam risk. It also increases engagement by making the reader feel valued.

• Customize Content Based on User Behavior: Tailoring content to align with past behavior (like purchase history) improves relevance and reduces spam triggers. This approach enhances user experience, showing attention to their interests instead of a generic message.

• Optimize for Mobile: Many spam filters check how well an email renders on mobile devices. Make sure your emails are mobile-friendly to boost deliverability and readability.

Technical Factors That Can Trigger Spam Filters

Several technical factors determine if your emails land in the inbox or get flagged as spam and locked in the spam folder. Here are the basics:

Sender Reputation and IP Health

The reputation of the IP address you send from significantly impacts deliverability. Frequent spam complaints, high bounce rates, or sending from a “cold” IP can damage reputation and reduce the chances of reaching inboxes. Make sure your IP has a good history of responsible email practices to keep your sender score high and your emails open.

Authentication Protocols (SPF, DKIM, DMARC)

Email authentication protocols (SPF, DKIM, and DMARC) work together to protect your emails from being marked as spam or used fraudulently. They do this by verifying that your email is genuinely from you, which helps it reach recipients and builds trust with email service providers.

• Sender Policy Framework (SPF): Checks if the sender’s IP address is authorized to send emails on behalf of your domain. This stops unauthorized sources from sending emails on your behalf, reducing spam risk.

• DomainKeys Identified Mail (DKIM): Applies a digital signature to emails, ensuring they haven’t been tampered with in transit. This helps recipients verify the email’s authenticity.

• Domain-based Message Authentication, Reporting, and Conformance (DMARC): Ties SPF and DKIM together and instructs receiving servers on what to do if an email fails authentication checks (e.g., move it to spam). It helps prevent email spoofing and improves domain security.

Using these protocols reduces the risk of emails being flagged.

Test Your Emails for Spam Before Sending

Testing your email before sending it ensures it gets to your audience. Here are some tools and methods to check if an email will get flagged as spam.

Spam Checkers for Content and Deliverability

Spam checker tools analyze your email’s content, keywords, phrases, and formatting that might trigger spam filters. These tools help ensure your email reaches its intended audience by flagging common red flags in your content and subject lines.

Here are some spam checker tools:

• Mail Tester: Tests the spammyness of your emails, providing insights on content and deliverability.

• GlockApps: Offers in-depth testing through major filters like Google, Barracuda, and SpamAssassin, helping optimize your emails before sending.

• Mailgun: Provides spam testing to identify issues that could affect your email’s deliverability.

• MailGenius: Analyzes your email for spam triggers and suggests improvements.

• MailReach: Another tool to analyze and improve email deliverability.

• Spam Analyse: Scans emails for spam risks and offers actionable feedback.

In addition to these tools, email marketing platforms like Mailchimp and HubSpot have built-in spam detection features. These platforms flag risky words or phrases that may affect your email campaign’s deliverability, giving you the opportunity to adjust your content before sending.

Preview How Emails will Appear Across Devices and Inboxes

Previewing how your email looks across different devices and inboxes ensures that the design and formatting remain consistent. Services like Litmus and Email on Acid let you see your email from multiple email providers and devices, helping you confirm that it appears professional and trustworthy everywhere it lands.

Avoid Spam Triggers for Reliable Email Delivery

Email campaign success depends on whether messages reach the inbox or end up in the spam folder. Avoiding spam-trigger words is crucial for deliverability. Emails using straightforward, honest language are less likely to be blocked.

Words that promise exaggerated benefits, like “guaranteed results” or “act now,” trigger filters as they mimic aggressive sales tactics. Vague terms like “extra income” or “fast cash” also raise red flags. Instead, use clear and specific language to build trust and communicate value. A professional tone also helps—greetings like “Hi [Name]” feel personal, while phrases like “Dear friend” can feel insincere or mass-marketed.

Review your emails for any high-pressure phrases like “apply now” or “last chance,” as these sound manipulative. Sticking to honest and informative language helps emails avoid spam folders and strengthens audience trust.

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Frequently Asked Questions (FAQs)

How does a spam filter work?

Spam filters analyze email content, sender reputation, formatting, and language patterns to detect potential spam. They use algorithms to flag emails with suspicious words, high-pressure language, or certain formatting styles that resemble common spam.

What is a good example of a basic spam filter?

A basic spam filter might scan for phrases like “earn money fast” or “limited-time offer” and assign a spam score based on the presence of these terms. The email goes to the spam folder if the score exceeds a set threshold.

What are spam-triggering words?

Spam-triggering words are terms often linked to aggressive sales tactics or too-good-to-be-true promises, like “free,” “guaranteed,” “act now,” or “fast cash.” Filters flag these since these words are common in unsolicited or spammy messages.

How to fix email deliverability?

To improve deliverability, check that your emails use clear, honest language, avoid spammy words, and maintain a good sender reputation. Authenticating your emails with protocols like SPF, DKIM, and DMARC also helps ensure they reach the inbox.

What is a good deliverability rate for emails?

A good email deliverability rate is generally 95% or higher, indicating most emails reach the recipient’s inbox rather than the spam folder.