Such an open from a mail program on a home, mobile or office network is classified at most as possible human activity. It says the message was displayed, not that it was read.
Previews made by chat apps or AI assistants when someone pastes a link are a different case: HawkOpen recognises many of them by their declared identity (R-OPEN-PREVIEW, R-OPEN-AI-DECLARED) and does not classify them as human activity.