You are factually wrong. You are indeed right that email was designed to be open, but because emails became unusable in that form about 20 years ago, every mail

You are factually wrong. You are indeed right that email was designed to be open, but because emails became unusable in that form about 20 years ago, every mail provider have deployed massive spam filters that rejects most unsolicited mails. Hence, currently, email is not open to unwanted emails, one have to go through many holes to arrive to mailboxes where he isn't invited. The filters are so good, that many people find that they can't even reach people that have asked them to subscribe to their mails, because they are still filtered out as spam. Enter MailChimp, the trusted mass mailer provider that help companies bypass the spam filters by giving their mail a respectable envelope. If they allow spammers their envelope shouldn't be respected. Actually, that's clearly the theme of the OP. And no, by using email I consented nothing. Where I live that's actually the law - I can sue whoever sends me commercial unsolicited email, unless given explicit permission (opt-in), spammer can be liable for compensation for each and every incident.