Have you used the words “free”, “help”, “percent off” or “reminder” in any of your recent email marketing campaign subject lines? Well, unfortunately your email open rates may be in a small bit of trouble. A recent study from Mailchimp revealed that these particular words were found to have a negative impact on open rates.
In fact, some would go as far as saying these words in emails could be considered as spam related words, therefore you could see more users unsubscribing or moving your email campaigns straight into the trash. Before you decide on the subject line for your next email campaign, try to think about whether the words you are using to entice your users could be misconstrued as negative or too promotional.
Some words that you could consider as alternatives that have seen a good increase in open rates, include; “sale” or “now”. These words offer clear call to action and are less overtly salesy, therefore the user would be more enticed and inclined to open the email and see the content within it.
Source: Unbounce (https://unbounce.com/email-marketing/5-mistakes-that-kill-open-rates/)