Since the breaches are becoming more and more common, there are a few websites to check if your account was among the "leaks". The ones I know of are https://haveibeenpwned.com/ https://www.hacked-db.com/ http://wasleaked.com/ Share if you are aware of others.
Is any one of these resources more credible than the other ones? Which has been around the longest and is the most reputable -- or are they all about the same?
Avira Identity Safeguard Allows iOS and Android Users to Check if Email Address Was Impacted by Gmail Breach
The thing with these lists is that those who are affected will probably never find out through these lists.