DoubleTick is a Chrome extension that adds read receipts to Gmail. When you enable tracking on an email, a tiny invisible image (a "tracking pixel") is embedded. When the recipient opens the email and their email client loads images, DoubleTick records that the email was opened.
What data we collect
When you enable tracking on an email, we store:
Email subject line — so you can identify the email in your dashboard
Recipient email address — so you know who opened it
Your email address — to associate the tracking record with your account
Open events — timestamp, approximate device type, and IP address of each open
What we do NOT collect
We never read, store, or transmit email body content
We do not access your contacts, calendar, or any other Google data
We do not track your browsing activity outside of Gmail
We do not inject any visible content, footers, or signatures into your emails
How data is stored
Tracking data is stored in Google Cloud Firestore (EU region: europe-west1). Data is associated with your Google account email and is visible only to you. We use HTTPS for all data transmission.
Data protection
We implement the following measures to protect your data:
Encryption in transit — All communication between the Chrome extension, our API, and Google Cloud services is encrypted using TLS (HTTPS). No data is ever transmitted in plain text.
Encryption at rest — Tracking data stored in Google Cloud Firestore is encrypted at rest using Google-managed encryption keys (AES-256), as provided by Google Cloud Platform by default.
Access controls — Each user's data is isolated by their Google account email. API requests are authenticated via per-user API keys. No user can access another user's tracking data.
Minimal data collection — We collect only the minimum data necessary to provide the read receipt service (subject line, recipient address, open events). We never access email body content.
No persistent credentials — We do not store your Google password or OAuth tokens on our servers. OAuth tokens are held locally in your browser and used only for Gmail API calls initiated by you.
Automatic deletion — Tracking records are automatically purged after 90 days. No manual intervention is required.
Data retention
Tracking records are retained for 90 days, after which they are automatically deleted. You can request immediate deletion of your data at any time by contacting us.
Third-party sharing
We do not sell, share, or provide your data to any third parties. Your tracking data is used solely to provide the read receipt service to you.
Permissions explained
Host access to mail.google.com — required to inject the tracking toggle into Gmail's compose window and display checkmarks in your Sent folder
Storage — stores your preferences and API key locally in Chrome
Notifications — sends desktop notifications when a tracked email is opened
Alarms — periodic polling to check for new opens
declarativeNetRequest — blocks the tracking pixel from loading in your own browser, preventing false self-opens
Your rights
You can:
Disable tracking at any time by not enabling the toggle on compose