Electronic mail is a method of transmitting and receiving messages using electronic devices. It was conceived in the late–20th century as the digital version of, or counterpart to, mail. Email is a ubiquitous and very widely used communication medium; in current use, an email address is often treated as a basic and necessary part of many processes in business, commerce, government, education, entertainment, and other spheres of daily life in most countries.
When a "robot" on Wikipedia makes changes to image files, the uploader receives an email about the changes made.
The mail or post is a system for physically transporting postcards, letters, and parcels. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century, national postal systems have generally been established as a government monopoly, with a fee on the article prepaid. Proof of payment is usually in the form of an adhesive postage stamp, but a postage meter is also used for bulk mailing.
A postman collecting mail for delivery
Many early post systems consisted of fixed courier routes. Here, a post house on a postal route in the 19th century Finland
The use of the Scinde Dawk adhesive stamps to signify the prepayment of postage began on 1 July 1852 in the Scinde/Sindh district, as part of a comprehensive reform of the district's postal system.
China 4-cent on 100-dollar silver overprint of 1949