> That's because people LIKE some unsolicited email. Unless you can distinguish unsolicited email that someone will like from unsolicited email that they won't like ...
Then they can opt into a service that sends them products they might like. Defaulting to opt-in, which is the current situation, is always terrible. Spam consists of a huge fraction of mail sent over the Internet, and vast majority don't want it, and it's a huge security problem (phishing, viruses etc.).
If Gmail implements this kind of protocol, then they can opt you into their advertising list as part of the sign up process.
Then they can opt into a service that sends them products they might like. Defaulting to opt-in, which is the current situation, is always terrible. Spam consists of a huge fraction of mail sent over the Internet, and vast majority don't want it, and it's a huge security problem (phishing, viruses etc.).
If Gmail implements this kind of protocol, then they can opt you into their advertising list as part of the sign up process.