25 words that you should avoid in your email subject lines

Email marketing may be an exact science, but crafting a good subject line for your emails is an art. You can get by with pretty much anything if your recipient is an acquaintance.

But marketing emails sent to relative strangers? There are rules for these type of things.

You don’t want to be flagged by the filters email providers have set up, which could easily direct your email message to the spam folder. And you don’t want to use words that might create distrust or doubts in the minds of your recipient.

For this reason, your subject lines are the most important part of your email campaign — even if your email is not opened, users will read your subject line, at the very least. With that being said, here is a list of 25 words that you would do well to avoid when composing your killer marketing email.

Not an exhaustive list by any means, just a rough guideline:

  • Free. This is, by most counts, the biggest word that triggers spam filters.
  • Sales offers like % off. You want to be selling without selling. Lines like save 10%, holiday sales, are tested failures, both among users and email filters.
  • Last chance. Nobody likes visiting the last chance saloon.
  • Like it or not, but the time for words like report, book, webinar has also come and gone. Talk about news, videos and posts instead.
  • WRITING IN ALL CAPS! No explanation needed.
  • Try and avoid names in subject lines, they are old school and make you look desperate.
  • Worse yet, addressing Peter as Paul by mistake wrecks your credibility.
  • Using FWD: and RE: to trick people into thinking your email is a part of an ongoing conversation. Deception, really?
  • Internet slangs. Few, if any, care for words like LOL, FTW and WTF.
  • Numbers. Quantifying your message might help, if not for the absolute fatigue users now have from constant bombardment of sales and promotional emails.
  • Awesome. Overused, overworked and clichéd.
  • Fancy text like smiley faces, stars, shapes, and oh the horror, hearts.
  • Don’t miss, save today, this week only are lousy words choices too.
  • As are words like donate, help and other such charity combinations. Unless you are a charity.

Leave a Comment Below

  • Sound advice Marcus. I think the underlying theme is just to be professional and don’t try to trick people because it won’t work. I agree completely.

  • All of these are definitely things to avoid. I laughed at your 1st bullet point because ANYTIME I see the word “Free” in the subject line I automatically delete it. An easy way to be considered spam.

    • Hahah! Great one, Randy! So true though. Great list Marcus. I need to bookmark these when I’m creating emails to send to customers!

  • % one is true. I don’t know why, but I occasionally get 40% off emails from Banana Republic and immediately delete them. Weird how it works.

  • A lot seem like common sense, but this is very helpful. It’s totally astounding how many of these mistakes (like using slang for instance) people make in an email subject or email in general!

  • Marcus- great read. I think the key is to just not be desperate or try to trick the reader. As you’ve identified, it’s pathetic and the reader can see right through it.

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