mit-ai was running its, not unix, and there wasn't even a port of unix to the pdp-10 at the time. moreover uucp addresses are of the form host!user rather than user@host
To clarify on account of kragen's idiosyncratic avoidance of uppercase, "its" is "ITS", the Incompatible Timesharing System, developed by MIT's AI Lab:
yeah, eventually, but in 01976 uucp was just getting started. even in 01978 i don't think they had a well-defined network map, though they said uucp already connected over 100 unix machines in the 7th edition manual. that post is from 01981
unfortunately 'show original message' is grayed out, so i can't actually see the map
