Here’s a great website that everyone (yes, that means you) should check out: https://shouldichangemypassword.com/ From the site’s homepage:
ShouldIChangeMyPassword.com has been created to help the average person check if their password(s) may have been compromised and need to be changed.
This site uses a number of databases that have been released by hackers to the public. No passwords are stored in the ShouldIChangeMyPassword.com database.
This website is made available as a public service.
After doing some very simple Google searching, the author of this site decided to do a genuine public service by making it known if your email address has been compromised. He did this by looking at plain, unencrypted database files which contained email addresses and their passwords. You should check this site immediately and see if yours is listed. Then, regardless of the results, change your email password. (Admit it – you haven’t changed it in a long time, have you?)