President Dwight D. Eisenhower established the Advanced Research Projects Agency in 1958, recruiting scientists to design the first large-scale computer network, which was intended to support the American military during the Cold War. Academics would use the network to communicate with one another via email between several US research universities.
Here’s a more fun bit of history.
If you wanted to send a message from one person to other, you had to personally add ALL the intermediate connection sites, like user@site1!site2!site3!destination-server, until it reached the server of the receiver.
And each of those hops were on a different relay forwarding schedule. So to keep costs low, site1 may only forward messages to site2 at night. It could take days for messages to reach final destination.
I had an old-timer explain this all to me over beers. We were laughing a lot.
I think that you’re thinking of UUCP.
https://en.wikipedia.org/wiki/UUCP
They were called “bang-paths”. I remember the first time I got an email reply in real-time. It was mind-blowing.
I’m still not convinced that this doesn’t happen to a lesser extent even now.
Seriously call someone and then send them an email and then just see how long it takes for the message to arrive. I’ve sent emails that have taken up to 3 minutes to get to their destination.
What’s going on, did it get lost on route, was it we way laid by highway bandits, how can it possibly take that long?
I mean you know that the Internet is nowadays instantaneous because accessing websites, instant messaging, online phone calls, etc. are instantaneous …
Email isn’t really intended to be used as an instant messaging system. A lot of the time, email clients are configured to only check for new emails periodically. Email servers might be configured to have some delay to avoid using too many resources at once. At least for me, emails (e.g. password reminder emails) do usually arrive within a few seconds, but indeed not always as immediately as instant messages.
I usually get notifications on my work phone about an email about 30 seconds before it appears in Outlook.