Donald Knuth, a renowned mathematician and recipient of the Turing Award (considered the Nobel Prize of computer science), retired from using email in 1990.
He issued a public statement on his Stanford faculty page, which I saved to Evernote 1–2 years ago. I think of it often, and my favorite portion is below:
“I have been a happy man ever since January 1, 1990, when I no longer had an email address. I’d used email since about 1975, and it seems to me that 15 years of email is plenty for one lifetime. Email is a wonderful thing for people whose role in life is to be on top of things. But not for me; my role is to be on the bottom of things. What I do takes long hours of studying and uninterruptible concentration.”