According to The Washington Post, email marketing drove 25% of all online sales on Black Friday. Meanwhile, PracticalEcommerce is reporting that email advertisements accounted for 22% of Cyber Monday orders.

Even though Black Friday and Cyber Monday happened a couple months ago, SendGrid’s Data Scientist, Victor Amin, has been looking at the marketing email SendGrid delivered during the largest shopping days of 2015. By analyzing the subject lines and delivery metrics of the marketing email we sent, we’ve come up with some great insights for email marketers, regardless of the time of year.

In this post, we’re looking into discounts in subject lines. One of the tactics used to increase engagement is including the sale amount, or percentage discounted, in the subject line of emails, like: “Save 20% On All Items” or “Shop the 50% Off Sales.” We wanted to see if this tactic was as successful as marketers assumed during Black Friday and Cyber Monday.

Most Common Subject Line Discount

Of the Black Friday and Cyber Monday marketing emails we sent, 38% included a discount in the subject line. The most common discounts were 20% and 50%, while other discount percentages were much lower:



Subject Line Discount Emails Don’t Perform Better

When compared to Black Friday and Cyber Monday emails that did not have a discount in the subject line, discount subject lines had lower engagement rates:


Although our modeling indicates that this is a statistically significant difference, it doesn’t account for a large portion of the variation in engagement rates between newsletters. Discounts in subject lines might perform well for some senders, but on average they actually have lower engagement than other subject lines!


[bctt tweet=”Discounts might perform well for some, but on average have lower engagement than non-discount subject lines!”]


Large Discounts Don’t Lead to High Engagement

When we looked at only the emails that offer discounts, we found that there is no statistically significant correlation between the size of the discount offered in a subject line and engagement with that email.



In the plot above, each point represents a 2015 Black Friday email campaign with at least 100 recipients. The green bars show the median engagement rate for each discount. As you can see, the engagement rates are all over the place.

Email Marketing Takeaways

While it may seem like including the amount of your sale is low-hanging fruit for improving engagement, that’s not necessarily the case. In fact, this tactic could have a negative impact on your engagement rates, depending on who is subscribing to your emails.

Every business and email list is different, so we suggest that you test what works and what doesn’t with your recipients. By A/B testing, you can determine which tactic works best for you. To learn more about testing your emails, download the SendGrid guide Why A/B Testing is Critical to Email Campaign Success.

Warren Duff
Warren is the Sr. Content Marketing Manager at SendGrid, specializing in email and content best practices, he develops many of the new guides you see SendGrid release as well as other pieces of content, including blogs, videos, case studies, and emails.