I filter email security scanners out of my analytics Safe Links, Mimecast and friends open every URL in an email before a human ever sees it. So I matched "outlook" in the user agent. Obviously a scanner.
Every proposal tool reports opens. Most of that number is link scanners, and "was it opened" was never the real question.
Closewatch scores each proposal and shows its work: "forwarded to someone else", "3m 51s on pricing", "came back on a later day". The dashboard is a call list, not a stats page.
Scanners are filtered out and only visible reading time counts. One link per recipient, so a second reader means it reached the person who signs.
It's the PDF you already send.