There are many Sent Emails with high total open counts. Why is this?
Each sent Approved Email has a 1px x 1px image embedded in the email. Whenever that image is rendered, an opened event is registered for that email.
In general, especially on MacOS and iOS device, there can be many opens registered due to preview panes that display images when the user scrolls up & down in emails. This is also the case with desktop Outlook clients. It is also possible that antivirus software or spam filters can trigger errant open events. There is no way to prevent this.
Certain email clients disable images. When an email is opened with images disabled, no opened event is registered.