Thee most commonly used network service is electronicmail (E-mail), or simply as mail.
最常使用的网络服务是电子邮件,或简称邮件。
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Telegraphs have been largely replaced by other forms of telecommunications, such as fax machines and electronicmail (E-mail), but they are still used in some parts of the world to send messages.
That file was electronic message, so suddenly in about 1971, we had e-mail. So an e-mail was pretty much the major use of the internet for the next 20 years.