Propensity to open is the likelihood a subscriber opens a message. It is calculated by looking at the percentage of emails a subscriber opened over the past X number of emails sent to that subscriber.
Senders use propensity to open to identify highly engaged or "super" subscribers. It is often used in situations that call for sending to engaged subscribers, such as an IP warm up, determining sending frequency, or when attempting to improve inbox placement at a mailbox provider such as Gmail or Microsoft.
- Over the past 10 emails sent to subscriber A, 5 emails were opened. The percentage of email opened is 50%.
- Over the past 10 emails sent to subscriber B, 3 emails were opened. The percentage of email opened is 30%.
Subscriber A has a higher propensity to open (is more likely to open) an email than subscriber B.