I'm going to guess Notes was one of them, but do you have any specific examples? (Unix™-derived e-mail systems being case-insensitive (although, I'd wager that

I'm going to guess Notes was one of them, but do you have any specific examples? (Unix™-derived e-mail systems being case-insensitive (although, I'd wager that /bin/mail was case-sensitive back in 7th Edition) is obvious, and I just checked our Exchange here on campus and it, too, cares not about the case of my recipient address.)