There are multiple online tricks that promise to hack someone’s email by intercepting its credentials. But the surest way to do it is to use spy software.
Being invisible to a target person, it tracks any activity another person does on the target device and delivers this information to an online account created for the spyware’s user.
That way, it’s possible to get to know the email’s credentials as well as the correspondence between people, contact details and any other email-related data. The most reliable apps for this purpose are mSpy, Spyera, XNSPY, Mobicip, SpymasterPro.