Apple's Mail Privacy Protection, implemented in September 2021, prevents senders from knowing if a recipient actually opened an email if the recipient is using the native Mail app. It does this by showing all emails in the inbox as opened. This means that your open rate contains "real" opens, along with machine opens. You can read more about this and how open rates work here.
As of July 22, 2022, you can view your total machine opens and machine open rate on your emails (emails before that date will show "--" instead of a number of machine opens).. This number is not deduplicated per activist. These statistics are mainly for informational purposes.
Note that this number will not be exact, and does not represent the performance of your email overall. We recommend using click and action rate for a more accurate analysis of your email's performance.
Machine opens are not targetable, meaning you cannot target emails to exclude or include machine openers. You can still target regular openers though, since many machine openers did indeed open your email (and it wasn't necessarily just the machine).