You can read the Web3 definition of 2013 below:
"The new iteration of the Internet based on serverless technologies comprising such features as: serverless data exchange, serverless electronic mail, serverless private networks, serverless social networks, decentralization, and these features are carried out by using peer-to-peer overlay computer networks operating over the Internet"
Thus, you can read the description of serverless e-mail in Web3 of 2013 below:
The method of organizing e-mail, which consists in the fact that e-mails are sent, forwarded, received and stored in the mode of constant connection of the computers of the sending and receiving users to the Internet, and in the mode of constant connection of these computers to the overlay peering computer network operating over the Internet in as nodes of this network, with obtaining network addresses of computers in this network, characterized in that the electronic messages are sent, forwarded and received through the current overhealing Internet peering overlay computer network by network addresses of computers on the network in accordance with the file transfer technology used in the network, the storage of electronic communications make to the email message on the information storage device, the user of the receiving computer.