"We also collect the content you create, upload, or receive from others when using our services. This includes things like email you write and receive, photos and videos you save, docs and spreadsheets you create, and comments you make on YouTube videos."
Their words not mine.
They have to to store it. Every third party email service collects the content you create, upload, or recieve. Even, under this definition, the "private" encrypted ones.
"We also collect the content you create, upload, or receive from others when using our services. This includes things like email you write and receive, photos and videos you save, docs and spreadsheets you create, and comments you make on YouTube videos." Their words not mine.