The first email was sent in 1971.
Why it is true
The first email in history was sent in 1971 by Ray Tomlinson, an ARPANET engineer. He chose the at symbol to separate the user name from the computer name, creating the format we use to this day.
Source: Computer History Museum
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.