If mail storage is the sender's responsibility, then perhaps senders should be allowed to seed their outgoing messages directly from their personal and home dev

If mail storage is the sender's responsibility, then perhaps senders should be allowed to seed their outgoing messages directly from their personal and home devices, and rely on others who have included their identity in their web-of-trust\address-book to propagate notifications of changes to their outbox, without relying on their ISP to do so. If the sender did not have at least one personal device connected to the internet 24/7, then they can perhaps purchase storage and bandwidth from a competitive online market, similar to the seedbox market for torrents, without surrendering their online identity or address to a commercial entity.