Investigating Subject Lines Length on Students' Email Open Rates

Instructors often prefer to use email for course communication. The use of emails has been widely discussed in the fields of marketing and behavioural design, but the prevalence of email in education makes it important for instructors to collect metrics on emails to see how students engage with them. One component of emails are the subject lines, which constitute as one of the first things a receiver sees before deciding to open an email. This poster discusses a case study at deploying an email intervention in an online CS1 course. We investigate how the length of subject lines impact the rate at which students open emails of a particular type that prompts them to start their homework early. We aim to share key results to inform instructors how to design their emails to better reach students. Further, we highlight the potential benefits for instructors when collecting and analyzing email engagement data.