Email is both faster and easier than traditional means of written communication (mail, telegraph, fax). It is easier than phone calls for mass data transfers, and can be sent and received at the convenience of the correspondents.
Speed : Email takes hours compared to days for hard-copy, and is only slightly slower than a direct phone call.
Ease: Email can be sent from nearly anywhere, especially from mobile devices and phones. It can be sent at any time and read whenever the recipient has time. It can be sent to multiple users without the need for copying, printing, or postage.
Storage: Computers can easily store, retrieve, copy, print, or forward emails.
Also, a small but important aspect is that electronic communication does not require the production of paper, or the use of fuel for transportation. It does require electrical power to transmit, process, and store the data, and the construction of facilities to perform these functions.