Great initiative but I see one major concern: Spam filtering. Most of the big mail providers provide spam mail filtering out of the box without which your inbox

Great initiative but I see one major concern: Spam filtering. Most of the big mail providers provide spam mail filtering out of the box without which your inboxes are bombarded with spam. This can be probably solved by spam checking by adding additional lambda, now you need more compute per mail, translating to more cost per mail, which makes it easy for malicious parties to send mail bombs and bankrupt you.