An open occurs in one of two ways: when a contact opens a message and images are loaded or when images are not displayed, but a contact clicks through a message.
Listrak is able to track an open when images are displayed because a tracking pixel is automatically inserted at the bottom of every message when conversion tracking is enabled. When Listrak is able to confirm that the tracking pixel has been displayed an open is recorded. If images are not displayed, but a click is recorded the message must have been opened in order for this to occur so the open is also recorded.
A read is counted when a message has been recorded as open for 5 seconds or longer.