Have you been "pwned" ?
Check to see if your email address has been breached by visiting the site https://haveibeenpwned.com/
This is a vast searchable database of known hacked websites that have been harvested for email addresses, passwords, mail server settings, credit/debit card numbers etc.
A "breach" is an incident where a site's data has been illegally accessed by hackers and then released publicly. Review the types of data that were compromised (email addresses, passwords, credit cards etc.) and take appropriate action, such as changing passwords.
Stay safe! Select the option to be notified of any future breaches for all of your accounts.