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There are certain words you don’t, can’t, shouldn’t, and mustn’t use within your email subject line if you want to pique people’s interest while avoiding spam blockers. 

It’s one thing if you’re sending a personal email to a prospect or customer — but if you’re sending mass emails, you’re not going to get very far if 90% of your messages get blocked before they ever reach their intended recipient.

There are so many spam trigger words, someone could write a nice thick book about them. Emails that promise untold riches and exclusive rewards reserved only for a special elite few. Remember that prince from Nigeria?

Let’s get into our list of words to avoid in email subject lines, so you can stay miles away from the spam folder.

Words Not to Use in Email Subject Lines

As with anything in life (except for maybe poker) you want to be open and honest with people. Be direct, be humble, avoid bragging and boasting.

Avoid words and phrases like the ones below so you can actually get your message in front of the people you want to reach:


1. Anything to do with money. 

Almost everything that’s associated with a dollar sign — think of your local used car salesman. You not only look sleazy in your email marketing, but the spam filters are sure to pick these up and they’ll never reach their destination.

  • Money back
  • Get paid
  • Cash
  • Dollars
  • Price
  • Big bucks
  • Credit or Debit
  • Profit
  • $$$

2. Marketing

Email marketing may be one of the most successful marketing channels out there, but that doesn’t mean email service providers want you clogging up their servers with it. You may be doing marketing when you email clients, but that doesn’t mean you need to remind them you’re doing it. 

Instead, provide actual content in your email that your readers will be interested in engaging with.

3. Exclusive

If you have a ‘special offer’ only for a select group of people, use any of the other words to tell people about it, but don’t use these ones.

  • Limited time
  • Get it now
  • Once in a lifetime
  • For new customers only
  • Offer expires
  • Deal ending soon

4. Superlatives

Leave the hard-sell advertising copy to Madison Avenue. Words like INCREDIBLE, and AMAZING smack of desperation and make you look fly-by-night. 

Let your product and your offer do the talking. Your prospects will figure out if you’re fantastic and amazing without you bragging about it.

  • Fantastic
  • The best
  • Perfect
  • Unbelievable
  • Wonderful
  • You will not believe your eyes!

5. Days of the week

This is especially true because of the flood of emails for things like Cyber Monday, Black Friday, Giving Tuesday, and so on. There are significant drops in open rates of emails with day names in the subject line

  • Today
  • Soon
  • Last Day
  • Friday before [holiday]

6. Earn

Again, anything that has to do with money, like earning extra income or earning cash, will not only drop the spam hammer, but people are too well-conditioned to believe its promises.

  • Double your income
  • Be your own boss
  • Increase revenue
  • Financial independence
  • Eliminate debt
  • Potential earnings

7. Free

This — and “bonus” — may be one of those words that make some people take notice, but many more see it as open-bait.

  • 100% off
  • Allowance
  • Gift included
  • Rebate
  • 0 down

Honorable Mentions

Emojis – Emojis and symbols ($$$) are major spam triggers.

All caps – CALM YOURSELF. Create excitement with your tailored content instead.

Excessive punctuation – It’s a sure way to let your reader know you’re cheap and unprofessional in less than 10 seconds. (Check this out!!!!!!)

Make Email Marketing Work for You

To start, try to avoid sending generic messages to everyone in your database. It can be difficult, especially with limited resources and pressing deadlines. But segmenting your audience, personalizing your messaging, and testing frequency can lead to improved open and click-through rates.

Hopefully, once you start building an email relationship with your prospects, your messages will make it to their inbox. But when you’re starting out with those initial conversations, don’t risk anything. Avoid the “naughty words” and keep on your prospects’ — and their email servers’ — good side.

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About the author

ZoomInfo

ZoomInfo combines the leading business contact database with best-in-class technology to pinpoint, process, and deliver the marketing and sales intelligence you need— exactly when and how you need it, to always hit your number.

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