Glassdoor sent the email with the addresses of more than 2 percent of its members, or over 600,000 people, clearly visible to other recipients.
Each address was made available to at least 999 other members, given that the emails were sent to multiple sets of users 1,000 at a time.
One of Glassdoor member Melissa Levine raised complain about this they did not keep their information private.
Source: https://www.databreaches.net/glassdoor-carelessly-exposed-600k-users-emails-suit-says/
"id": "GLA1503622",
"linkid": "glassdoor",
"type": "Breach",
"date": "08/2016",
"severity": "60",
"impact": "4",
"explanation": "Attack with significant impact with customers data leaks"