Pickup email makes one problem in spam much worse. It demonstrates that the address being spammed is valid and active. That's one of the reasons most email clie

Pickup email makes one problem in spam much worse. It demonstrates that the address being spammed is valid and active. That's one of the reasons most email clients/hosts don't load remote resources by default. Unless there was a google-scale grab-n-cache going on for those messages, I think there'd be a problem.