← Mailskin

Privacy Policy

Last updated September 3, 2026

The short version: Mailskin does not collect, transmit, sell, or store any of your email content, contacts, or Gmail activity — anywhere, ever. It runs entirely inside your browser. The only data that ever leaves your device is a license key check, and only if you use Mailskin Pro.

What Mailskin is

Mailskin is a Chrome extension (Manifest V3) that injects a content script into mail.google.com to change how Gmail looks and behaves in your own browser tab — label placement, snippet length, color themes, and (for Pro users) tracking-pixel blocking, VIP sender highlighting, stale-email flags, and auto-label rules. It has no backend server, does not use the Gmail API, and does not request Google OAuth access to your account.

Data we never see

Because Mailskin has no server and no API access, the following never leave your device — there's no way to receive them even if we wanted to:

  • Email content — subject lines, message bodies, attachments
  • Contacts or sender/recipient lists
  • Gmail account identity, login credentials, or OAuth tokens
  • Browsing history outside mail.google.com
  • Analytics, telemetry, or usage tracking of any kind

Data that stays on your device

Your Mailskin settings — layout choices, theme, VIP sender list, auto-label rules, and the Pro license key if you enter one — are stored using Chrome's built-in chrome.storage.sync API. This is the same mechanism Chrome uses to sync your bookmarks and browser settings across your own signed-in devices; Mailskin does not run or have access to a separate server for this. This data is never sent to Mailskin's developer.

The one network call Mailskin makes

If — and only if — you enter a Mailskin Pro license key, the extension calls Polar's license API (api.polar.sh) to activate and periodically revalidate that key. This call sends the license key and a device identifier used for activation-limit enforcement. It does not send any email content, sender information, or Gmail data of any kind. Polar acts as our payment and license processor; see Polar's privacy policy for how they handle that data. Free users' devices never make this call.

Permissions, explained

Permission What it's for
storage Saves your settings locally/synced via Chrome — no content, only preferences you set.
alarms Schedules a once-daily Pro license revalidation and stale-email timing checks.
sidePanel Hosts the settings UI in Chrome's native side panel next to Gmail.
Host access: mail.google.com Lets the content script read and restyle the Gmail page you already have open. This is the entire mechanism of the extension.
Host access: api.polar.sh Used only for Pro license activation/validation, described above.

Children's privacy

Mailskin is not directed at children and does not knowingly collect data from anyone, of any age — see above.

Changes to this policy

If this policy changes, the date at the top will change and the update will be reflected in the extension's Chrome Web Store listing. Material changes are also visible in the GitHub repository's commit history, which is public.

Contact

Questions about this policy or how Mailskin handles data: see the support page, or open an issue on GitHub.