What Words Will Send Your Email Message to SPAM?

What Words Will Send Your Email Message to SPAM?

Over the years, I’ve tested enormous email marketing campaigns both for myself and various clients online. I’ve been surprised at what I found, especially when much of my research has been based on email deliverability, avoiding messages going to SPAM. I’ve done various SMTP testing, taken part in various email case studies, and I’ll be publishing one of them very soon on my blog. However, it’s important we understand what the factors determining email deliverability are. For example, here’s what I’ve learned so far:

Email deliverability has much to do with:

  • Sending IP Address;
  • Words or phrases within email;
  • Reputation of sender;
  • Subject line;
  • Body;
  • History and reporting.

Today, I’d like to discuss one element of my testing based around wording and phrases. I’ve noticed what you write within your email subject and body will directly influence your email deliverability. Here’s what my research has shown.


The Word “FREE”

Many smart email service providers or ESP’s always keep a track of data gathered, like how often people report SPAM. When I was running a test using the word FREE within the subject and body, 90% of the time, it went into SPAM. I believe, over the years, people did bulk email sending, where they bombed email boxes with CPA offers containing the word “FREE”. Some good examples of these types of offers are:

  • Earn FREE $5.00 when you take this survey;
  • FREE $50.00 for your opinion;
  • Get a FREE service quote;
  • etc.


What tends to happen with these types of emails is that you’ll fill something out and be taken to all paying offers, etc. Not to mention, they have you automatically opted into many other email lists, which is NOT good if you are trying to avoid certain messages. Anyway, with a proven track record of NO success, people often report these as SPAM and going forward, emails containing the word FREE is sent into junk mail.

Adding a “$” with “FREE”

This is like the above example, however, it’s important to note that in one example, you can use “FREE” without the “$” sign and still be directed into the SPAM box. Many times, people will send email messages claiming you’ll earn money for FREE or for performing a desired action. History has shown this is NOT the case and many ESP’s will send your message into SPAM for this. When I performed tests using SMPT providers like SendGrid, SMPT.com, etc., I split tests using different subject and headline, finding that 90% of the time, these two things combined, “$” + “FREE”, was automatically considered SPAM.

Character Length

I’m adding this to the factors because the “lack” of words is directly responsible for how your message will be received. For example, if you send out a very short message, then it will be too suspicious and handled different by clients like Gmail, Yahoo, and Hotmail.com. For example, take a quick look at some of the SPAM mail you are receiving right now or even yesterday. You’ll notice the following:

  • They are short in characters;
  • They contain a number or words “FREE”;
  • Are sent from a suspicious email provider.

All of these factors combined affect email deliverability so you want to be careful when sending out follow-ups. Why? You can still be a legit business and need to send out special offers so you’ll want to be careful putting together your messages. However, you have leverage on your side simply because many people you are sending out messages to have opted into your newsletter.

Today I'm just looking at "words" which contribute to poor email delivery however there are other factors you should pay close attention to. For example, email deliverability can be affected if you are sending from a backlisted or blocked IP address. This is very common if your using a shared SMTP rely. Next, email delivery can be affected if the receiver has specific filters in place so it's important you keep testing until you find out the right combination.

Here they are in point form again:

  • Blocked IP address (maybe use a dedicated IP address when sending through SMTP relays);
  • Receiver filter in place looking for specific keywords, etc.;
  • Character length.

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