We track opens on all html-based campaigns by embedding an invisible, 1-pixel image in your campaign. When a contact opens your email and chooses to display the images in your email, that graphic is downloaded from our server and it's recorded as an open.
If a contact chooses not to display images, their open may still be tracked if they click on a link contained in your campaign or automation email. Note that link tracking will need to be enabled for this option.
It is not possible to track opens for plain text emails.
Note that open rates are not recorded for contacts who use the Apple Mail app with iOS 15 with Mail Privacy Protection (MPP) enabled. To learn more, visit ActiveCampaign and Apple iOS 15 Mail Privacy Protection.