Electronic mail, often abbreviated to e-mail, email, e-post or originally eMail, is a store-and-forward method of writing, sending, receiving and saving messages over electronic communication systems.

The term "e-mail" applies to the Internet e-mail system based on the Simple Mail Transfer Protocol, to network systems based on other protocols and to various mainframe, minicomputer, or internet by a particular systems vendor, or on the same protocols used on public networks.