Study finds iOS 15 is inflating email open rates

Apple’s new Mail Privacy Protection (MPP) is having a significant impact on email marketing, according to a new study from Campaign Monitor that found that average open rates were up 3.5% year-over-year in 2021, while click-to-open rates were down 3.6%.

Released last year as part of Apple’s iOS 15, MPP is an opt-in feature that essentially blocks email senders from being able to see information on how those users interact with emails. It does this by pre-fetching/downloading an email and its images (including tracking pixels). This marks the email as opened, artificially inflating open rates for each user that has opted in to the new feature. 

The study found that open rates increased by more than 10% between June 30, when iOS 15 went into its public beta release, and the end of the year.

Why we care: This is further evidence that open rates are, at best, a questionable KPI. Even before this there were very real questions about the use of a metric that had no connection to engagement. Someone who opens an email and immediately trashes it is counted the same as someone who opens it and then clicks through to an offering.