You mean like with Google's G-Suite? Admins can always change your password to one that they know and log in with it. Even with a 2FA policy, they can generate

You mean like with Google's G-Suite? Admins can always change your password to one that they know and log in with it. Even with a 2FA policy, they can generate backup codes to use. Generally assume that yes, corporations can read their corporate email accounts. However, they may have policies that prevent their staff from accessing other employees email accounts without a specific need.