Flexus TrackMail adds a read-receipt style signal to the inboxes you already use. When you send a tracked message from Outlook or Gmail, a tiny open pixel (and optional click wrappers) lets us record engagement.
In Gmail, double green checkmarks appear next to sent mail once an open is recorded. In Outlook, the Flexus TrackMail task pane shows open counts, last-open time, and click CTR for the contact thread.
Proxy opens (common with Gmail and Yahoo image proxies) are labeled so you can treat them differently from a clear desktop open. That keeps follow-ups honest.
Best practice: wait for a real open or click before nudging, and keep the reminder tone helpful rather than “I saw you opened this.”