According to the search engine, emails are scanned for messages already stored on Google's servers, such as those in transit.
A Google spokesman said users "implicitly consented to this practice" by having a Gmail account.
“Our automated systems analyze your content (including email) to provide you with relevant tools, such as custom search results, targeted advertisements, and spam and malware detection. This analysis occurs while the content is sent, received and when stored, ”said the company.
