Firefox provides a new service, Firefox Monitor.
You can check how much your personal data breach on the Internet. Just enter the email address which you used on the Internet. Click search Firefox Monitor.
For example, I entered an email I used more than ten years. it told me that this email appeared in 10 data breaches.
You can sign up to use this tool to monitor your email. When a new data breach happened, and the monitor found your email is in the list of it. It will send you an email to notify you.