i think the last time this discussion came up on HN, the conclusion was similar: https://news.ycombinator.com/item?id=30491518 https://news.ycombinator.com/item

i think the last time this discussion came up on HN, the conclusion was similar: https://news.ycombinator.com/item?id=30491518 https://news.ycombinator.com/item?id=30491518 they're not really spam sources but the other criticisms of email tracking/cross marketing apply.