Shaun Nichols and Iain Thomson wrote an article that proposes to list the top ten industry-changing software applications. I wouldn't dream of arguing with their choices, since they are getting a ton of comments on that subject. Nor do I quibble with the idea of naming the ten most important advances. Articles about "the N most X ..." tend to be “dug” to the digg.com web site. One of these days, just for the publicity, mind you, I might do a photo essay on the ten most common types of lint that collect in a gas dryer.
Item #4 on this list is “SNDMSG”, a 1971 invention. Here's what Shaun Nichols says, in part: ... a nifty little program called SNDMSG. The program allowed users to send messages through ARPAnet to users on computers connected to other networks. In other words, Ray Tomlinson invented email.
Only Ray Tomlinson didn't. I can testify that I was one of thousands using an email application in January 1968, and the technology I used was available in 1966. (The Wikipedia article on Email mentions Email on mainframes in 1965.) SNDMSG enabled people on different computers to exchange messages. But in the 1960's many, many people used teletypes to dial into to shared computers that acted as servers for email. We exchanged technical messages with our peers, coworkers and customers, and no one cared how many computers were involved in the process.
I might just mention two more things about email in the 1960's: It was slow (ten characters received per second). And, there was no such thing as spam.