Sometimes people get emails that make it clear their personal network is known to various websites or agencies.
Really, there's no privacy. Here are a couple of examples.
I heard in a talk by a cyber security specialist that the phone manufacturers and telcos were actively collecting location data long before anyone knew, and long after they said they'd stopped. They were mapping all the locations of all the Wifi access points everywhere. That allowed them to very closely locate individual's locations far beyond triangulating from cell towers or GPS. Which in turn allowed them to map out not only the comings and goings of the people in "meatspace" but to determine the relationships between the people as they spent time in each other's presence at certain times. Bear in mind that these are the same people whose platform you use to send your emails & texts, and make your calls.