Zillow Hijacks Other Emails

For the past several weeks, whenever I open a Zillow email, all other emails opened after it, show the Zillow email. The only way I can get Zillow to stop "hijacking" other emails is to sign out and sign in again. I have unsubscribed to Zillow many times and still get emails from them. Has this happened to anyone else? Or does anyone know why this is happening? Thanks!