Have you ever waited impatiently for an important email, wishing your internet connection wasn’t so slow? When that email arrived, did it generate more questions than answers?

If that has been your experience, you are not alone. The recipient of the very first email had the same reaction. The message itself seemed to foreshadow the excitement and frustration that would forever haunt this new means of communication.

It was October 29, 1969. UCLA computer science professor Leonard Kleinrock and his graduate assistant Charley Kline prepared to send the first computer-to-computer message. They were using ARPANET, the precursor to the internet. It connected universities that contributed to the Department of Defense’s technology enhancement program. At the time, only four universities — UCLA; Stanford; the University of California, Santa Barbara (UCSB); and the University of Utah — had computers.

Kleinrock and Kline’s message was not going to be long — just one word: “login.” Even this one-word transmission proved to be too much for the room-sized computer. After sending the letters L and O, the system crashed.

After restarting the network, they tried again. This time, it was successful. It was a revolutionary achievement for technology, but not for speed. It took one hour to transmit that single word.

It wasn’t until two years later that MIT researcher Ray Tomlinson sent an electronic message to himself, introducing another staple of email communication. He used the ARPANET to send a message between two adjacent computers, using two programs called SNDMSG and READMAIL that allowed users to leave messages for one another on the same machine. He incorporated a third program called CYPNET for sending files between computers. In effect, he had developed a system for sending information from one user to another on different computers.

Tomlinson’s first message has been lost to history. He said that it was nothing profound — basically a variation of “QWERTYUIOP.” It was how he chose to address that message that was most memorable. He used the “@“ sign to designate the recipient of the message.

Billions of emails have been sent since then (most of which, coincidentally, seem to end up in the inbox of this writer). We can thank Tomlinson for each of the @ symbols that direct every message. We can also thank Kleinrock and Kline for establishing the precedent that the messages for which we wait the longest are the ones that make the least amount of sense.