OneDollarTrack Gmail Open Tracking

About

A minimal, privacy-respecting Gmail open-tracking extension for personal use.

   OneDollarTrack Gmail Open Tracking tells you when an email you sent from Gmail has been opened. It is intentionally narrow: no click tracking, no analytics dashboard, no marketing features, no Outlook support.

   How it works:

   - Detects Gmail compose windows and attaches a lightweight send listener.
   - Just before Gmail sends a message, it registers a unique `message_id` with the OneDollarTrack backend and injects a hidden 1×1 tracking pixel into the outgoing HTML.
   - When the recipient opens the email, their mail client fetches the pixel, which our backend records as an open.
   - The extension periodically polls the backend (every ~1 minute via `chrome.alarms`) for status updates on messages you sent in the last 7 days.
   - A compact badge appears next to your sent thread in Gmail showing `Not opened` or `Opened N times` with first/last-open timestamps on hover.
   - The first time each message is opened, a local Chrome notification fires.