I know gmail does some image caching / proxying. https://news.ycombinator.com/item?id=6898454 https://news.ycombinator.com/item?id=6898454 I guess the vector

I know gmail does some image caching / proxying. https://news.ycombinator.com/item?id=6898454 https://news.ycombinator.com/item?id=6898454 I guess the vector here is when you read an email versus where from / using which device / etc.