In this mostly-good article about how to create an application that competes with email, Chuq says "What is email? It is:
- A way to move a message from a sender to a recipient
- A place to store that message pending delivery (and for long-term storage)
- A way to get that message to a recipient."
I kind of agree, but have significant changes to all three. It is:
- A way to move a message from a sender to one or more recipients
- A method to (a) store that message pending delivery and (b) tell the sender if the message didn't get delivered
- One or more ways to get that message to a recipient for viewing and long-term storage
Update: Tony Finch sent me a much more succinct definition that also encompasses something both Chuq and I missed: "A way to move a message from a sender to one or more recipients without any prior arrangements".