Crouching Tracker, Hidden Email

Introduction: When a webpage shows a link with your email embedded as part of the link, it may be an attempt to track you.

e.g. http://www.example.org/free_stuff?invite=user@example.com

This extension will change the cursor when you mouse over links containing the "@" symbol to give you an indication that you may be tracked and to proceed with caution.

This tactic has legitimate uses such as for email verification when signing up for new services, but it is also used by spammers or phishing emails that invite you to click on a link which then tells the server that your email address is active and even prefills your email in the webpage so that they look trustworthy.

Details:

This extension only works on absolute URLs because most trackers need to redirect to another domain that is not within the control of the current website. This means relative URLs, FTP links and mailto links are safe and are excluded.

• Relative URLs: /non-existent?q=user@example.com
• FTP links: ftp://www.example.org/?q=user@example.com
• Email links: mailto:user@example.com

For maximum privacy, this extension achieves the task using pure CSS.

As a result, this extension will catch all URLs with the "@" symbol regardless of whether it conforms to a valid email syntax. For example "1@1" will be treated as an email address.

URLs which use the "@" symbol for stylistic purposes will also be treated like an email.

e.g. https://twitter.com/@Twitter/status/1390725076996268038

This extension will also obviously not work for links put through URL shortener services such as Bitly.

Addendum:

Due to the security restrictions on this addons.mozilla.org website, the extension cannot run on this webpage so it cannot change the cursors here.