The Verge is reporting that “Pokémon Go has become wildly popular in the days since its release last week, but the app may be hiding a serious security issue. 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” (Source). Read more at The Verge.
Perhaps the app developer will correct this issue in the near future.