2.9 billion – the number of projected worldwide email users by the end of 2019. One-third of the entire population of the world is hearing “You’ve got mail!” on a regular basis.

But even with an ever-growing number of messages ending up in our mailboxes, more than  70% of consumers rank email as their top channel for marketing communications .

But in order to make sure your email marketing efforts are effective,  you need to ensure your prospects are receiving your messages . That means understanding email spam filters and figuring out how to avoid being trapped in them. Here’s what you need to know.

How do spam filters work?

There are different types of spam filters, all of which work to keep junk out of people’s mailboxes. Some are provided by the email service; others are customizable by the recipient.

  • Header filters: These filters review email header content for suspicious information, including IP addresses typically associated with spammers or mass copies of the same email sent to groups.
  • Content filters: These filters are more sophisticated and review the content of a message for specific words and patterns that indicate spammy behavior. Examples include overuse of money-related words, like “free,” “discount,” and “lottery”; adult terminology; or words that push overly-urgent action, like “hurry” or “last chance.” While a single incidence of these words may not be enough to trigger the content filter, they should be used judiciously.
  • Language filters: These filters can remove any emails not in the recipient’s native language. Similar filters can also be used to block emails that come from outside the recipient’s country.
  • General blacklist filters: These filters stop all emails that come from a blacklisted file of known spammers.
  • Rules-based filters: These filters are created by the user to sift out emails that don’t give them value. The user may choose to filter out certain senders or phrases in an effort to reduce the spam making its way into their inbox.

As with all technology, spam filters are continually improving and becoming more sophisticated, with newer iterations analyzing text within images or reviewing the context in which specific words and phrases are used.


How can I get my marketing emails past the spam filters?

With so many spam filter pitfalls out there, and so many potential opportunities to trip yourself up, what can you do to give yourself the best chance of landing in your prospects’ inboxes?

1. Maintain a clean email list

If your email list contains outdated addresses or unengaged subscribers, you’re probably not getting the delivery rates and open rates you’d hoped for. When that happens, your messages are seen as less relevant, and that can play a factor in whether you’re sent to spam or not.

Using email verification tools can give you a quick and easy option to clean up your list and boost engagement rates from your users by creating a higher ratio of engaged recipients.

2. Exclude the “fancy” stuff

Emails should have a good balance of text to images and other information. Building emails that are all image and no text, all code and little text, or that have “fancy” embedded information like video, can drag you down and create the appearance of spaminess.

3. Create good subject lines

Just as subject lines can affect your recipient’s engagement with your product, those first impressions can have an impact on your ability to make it into inboxes at all.  69% of email recipients choose to report messages as spam based on the email subject line alone , so create subject lines that are relevant, useful, and low on exclamation points and ALL CAPS.

4. Invest time and resources into making your email content engaging

If you create content your recipients want to read, you’ll earn a better sender score. If your content is boring or overly salesy, more of your prospects may mark it as junk or ignore it, both of which can affect your credibility and lead to your messages being trapped in spam filters. Understand the elements that convey credibility. Don’t claim expertise you don’t have. It’s too easy to check someone’s background these days to risk your reputation on falsehoods.

5. Don’t use spam trigger words

The best way to avoid being sent to spam is to … well, avoid acting like spam. Using spam trigger words can increase the possibility of being trapped in a spam filter. When you’re creating an email, find ways to convey relevancy and value, but  avoid the following terms and phrases , or use them sparingly:


Money, money, money

1. $$$
2. Additional income
3. Affordable
4. Amazing bargains
5. Bargain hunter
6. Cash back today
7. Consolidate debt
8. Deals
9. Earn cash back
10. Easy money
11. Eliminate debt
12. Extra cash
13. Extra income
14. Financial freedom
15. Full refund
16. Get more for your money
17. It’s a bargain
18. Lower fees
19. Lower interest
20. Lower rates
21. Make more money
22. No cost
23. No hidden costs
24. No startup fee
25. No upfront costs
26. One-of-a-kind deal
27. Pure profit
28. Risk-free
29. Save big
30. Save big money
31. Start saving immediately
32. Why pay more?


33. 0%
34. 100%
35. 99.9%
36. Be your own boss
37. Bonus
38. Boost sales
39. Boost vitality
40. Enhance performance
41. Free
42. Free 30-day trial
43. Investment opportunity
44. Join the millions …
45. Just reduced
46. Money making opportunity
47. No catch
48. No questions asked
49. Refinance and save
50. Risk-free


51. Act now
52. Amazing benefits
53. Amazing offer
54. Bonus offer today only
55. Brand new
56. Buy now
57. Call now
58. Clearance
59. Expiring today
60. Fast cash
61. Get it now
62. Get it today
63. Incredible deal
64. Instant access
65. Instant download
66. Limited-time offer
67. Limited supply
68. One-of-a-kind offer
69. One-time fee
70. One-time offer
71. Pennies on the dollar
72. Special deal
73. Special discount
74. Special offer
75. Take action
76. While available
77. While in stock
78. While supplies last


79. Advertisement
80. Free download
81. Free leads
82. Marketing solution
83. Not spam
84. Search engine
85. Visit our website
86. Web traffic
87. Online leads

All the Other Free Stuff and No Stuff

88. Free add-on
89. Free consultation
90. Free download
91. Free gift with purchase
92. Free installation
93. Free option
94. Free sample
95. Free trial
96. Free trial period
97. Free unlimited access
98. No application
99. No cost
100. No investment
101. No obligation
102. No restrictions
103. No strings attached


104. !!!
105. #)(@#$
107. Anything R-rated
108. Hot
109. Extra.Punctuation.Between.Words.
110. Score with …
111. S p a c e s b e t w e e n l e t t e r s



Trying to navigate spam filters can be frustrating, especially if you’re in an industry that relies heavily on some of these terms (think banking, financial services, and marketing in particular).

However, you may just need to think creatively and use your storytelling skills to go beyond feature-oriented terms and highlight the benefits you can provide to potential customers.

As a businessperson or a marketing professional, you’re investing time and money into creating a product or service your customers need, then spending even more time and money on putting together exceptional communications to spread the word about your company.

However, even your best marketing is only as good as its deliverability rate. Avoiding these trigger words won’t automatically put you at the top of your prospect’s mailbox, but it can help your chances.

The rest is up to you.

How Do Spam Filters Work? 100+ Spam Trigger Words to Avoid


PS. Imagine running a SaaS business and having to deal with “free trial” as a spam phrase.