"In many cases, users who sign into the app through a Google Account are often inadvertently granting broad permissions over all information linked to the account, including the power to read and send emails. At no point in the sign-in process does the app notify users that full access is being granted."
http://www.theverge.com/2016/7/11/12150468/pokemon-go-privacy-full-account-access-permission
Its spyware and easily takes over.