700K accounts from mSpy (mspy.com) were exposed in this breach. Besides email addresses, it included device usage tracking data.
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Device usage tracking data
In May 2015, the "monitoring" software known as mSpy suffered a major data breach. The software (allegedly often used to spy on unsuspecting victims), stored extensive personal information within their online service which after being breached, was made freely available on the internet.
Source: Have I Been Pwned (CC BY 4.0)