A history lesson
These days, one user typically owns his own computer system. You have a personal laptop, gaming desktop or (worse) mobile device. So it is forgivable to forget that MacOS still allows multiple isolated user accounts on the system. These are full Unix user accounts with the same permissions and home directories that would be familiar to users of any other *nix.
And not that long ago, think 90s to early 2000s, it wasn't unusual for multiple users to share a family computer. If you wanted everyone playing nice, you'd create separate user accounts for each user. This would ensure that Jonny couldn't accidentally delete his sister's homework. Except if they were users of Windows 98, where you could access anyone's files on the same hard disk. If you were on a serious system like Linux, the permissions were actually enforceable.
Now MacOS, erstwhile OSX, has its heritage in Unix. The big old mainframes, minicomputers and workstations of the 70s and 80s were its domain. You'd have multiple remote users sharing the one computer system, accessing it remotely through terminals.
So what if these users wanted to talk to each other? What if you wanted a message to be sent to a fellow user, where he would find it waiting in his inbox? This is why the mail utility was born. And the same utility still exists in Mac OS 12.7 Monterey.
Sending mail
To send a mail message, first open the terminal. Simply type mail <username>, i.e. the local user name of your recipient. You'll then be prompted for a subject, type this then hit Enter. Then your message body, type this then hit Ctrl + D to send your message:
Sending myself a lovely message.
Each time you open the terminal in the future, you will be presented with the line 'You have mail.' This will show until you empty your inbox:
You mean someone thought of ME?
So type mail (no arguments) to get a listing of your inbox. Most curiously of all, this also shows the copyright date of the mail utility. It dates from the 6th of June, 1993:
Mail on Mac OS 12.7, an OS from 2021
That's right, the mail utility on Mac OS 12 is over thirty years old!
But I was mistaken about something! Mail wasn't just for messaging local users. Looking at the manual page, we see the mention of long dead networking protocols like ARPA and UUCP mentioned:
Yes, mail can contact other machines, just none of the living ones.
Why care?
Now what's the use in keeping this ancient utility on a modern OS? MacOS presents itself as a slick and modern operating system. Yet under the modern garb the ancient roots run deep; I find this reassuring, it reminds me that it is still a full Unix system at my disposal, with all the power and heritage that entails. Let's hope it remains that way.
