“Engagement could easily drop for campaigns if subscribers are just ‘peeking’ at—and not reading— your campaigns. If you’re seeing your engagement rates dropping, consider revamping your content, optimizing your inbox view, and ensuring your messages are mobile-friendly.”
Last year, Apple launched the latest version of their operating system iOS 9, which included new email viewing features called “peek” and “pop”. The former allows a user to preview an email inside a modal window without actually opening the email. However, a “peek” will register as an open to most ESPs. Watch these interactions carefully moving forward; the number may say one thing, while your audience isn’t getting the full benefit of your emails.