298K accounts from Ancestry (ancestry.com) were exposed in this breach. Besides email addresses, it included passwords, which makes it a high-risk breach.
Was your email address in this breach?
We display where your address leaked and what went with it. We never store the address.
We don't store your address. It is checked right here against about 1029 breaches, including this one.
Email addressesPasswords
In November 2015, an Ancestry service known as RootsWeb suffered a data breach. The breach was not discovered until late 2017 when a file containing almost 300k email addresses and plain text passwords was identified.
Source: Have I Been Pwned (CC BY 4.0)