We provided some volume and engagement data and insights earlier in the week in our post, Black Friday and Cyber Monday – Using Data to Gain Email Insights. Today, we’re expanding on that data with some email subject line analysis. SendGrid’s Victor Amin, Data Scientist, looked at data from Black Friday and Cyber Monday in 2014 to see if there are any takeaways for senders.

Below, we’ve provided some of the plots we think are interesting about subject line wording. You can find some potential takeaways at the end.

Subject Line Wording

In addition to the volume, engagement, and usage data we gathered originally, we wanted to see if there were particular words that occurred more often around Black Friday and Cyber Monday. Our data showed the following:

When we made predictions about email volume in our last post, we thought email volume would peak in the days leading up toBlack Friday and Cyber Monday. We found that email volume actually peaks on Black Friday and Cyber Monday respectively, so it makes sense that corresponding Black Friday and Cyber Monday wording, (“friday,” “your,” “black,” “off,” “monday,” and “cyber”) all peaked in usage during the weekend last year. A couple interesting takeaways from this include:

  • “Your” usage – “Your” is a very popular word for subject lines because it allows senders to convey a sense of familiarity with the recipient. During Black Friday and Cyber Monday, however, the word dips in usage. This could be pointing to mass emails being less targeted.
  • “Off” usage – The spike in usage of the word “off” is interesting because it likely corresponds to the percent items are discounted at different sites (40% off, 25% off, etc.)

To further our look at sale language in subject lines, we decided to look at how often marketing emails included discount percentages in their subject lines:

We found that in Black Friday-related subject lines, 50% was the most common discount, followed by 10%, 75%, and 40%. Even more interesting was how people engaged in these emails:

The plot above shows that email engagement rates don’t appear to be related to discount size. While we expected engagement with high discount percentages to be much higher than lower percentages, this data showed otherwise. This could mean that recipients who are already engaged with your emails will click on messages regardless of discount.

Conclusion and Takeaways

If you’re planning on sending Black Friday and/or Cyber Monday marketing emails to your recipients, there a couple things you may want to keep in mind:

  • Re-Word Your Subject Lines – If your recipients are being sent numerous emails that all contain very similar subject lines, you may want to think about sending something more unique. Think of ways that you can stand out from the crowd.
  • Make Sure Your Recipients are Engaged – Since we determined that the amount of the discount offered in the subject line had no correlation with the engagement rate, it’s more important to make sure the people receiving your messages are the ones who want them and will open them. 
  • Test Your Changes – If you’re considering making changes to your subject lines, it’s a good idea to use A/B testing to test your alterations against your traditional subject lines to see if those alterations do impact engagement.

We’ll be doing more subject line analysis about marketing email in the future, so make sure you check back on the SendGrid blog to see what new insights we’ve gained. And for more email data insights from Victor, check out some of his other studies on the blog.



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.