Email is our only reliable communication method between different organizations. I'm still of the opinion there should be public-option internet services. Everyone deserves an e-mail address that cannot be taken away from them without a court order.
There are many decisions that impact the usability and cost of the service. Some people need high volume sending or large mailbox storage. Do you punish people for sending spam? Do you filter spam, if so, how. Do people need public terminals to access the service? Etc.