- "Hey I'm most in a sea of spam!"

- "That's what rules and folders are about. It astonishes me how few people like to spend days constructing manual filters to weed out spam from their inbox"

Someone adds Bayesian filtering to MUAs/MDAs, classifying mail as (SPAM|NOT SPAM). The world rejoices as the intricate filter building interface got reduced to two buttons, and the complexity of combating spam went from O(n) to O(1), and email became manageable again.

Fast forward to present time

- "Hey, now that the problem of spam is solved, email is useful again. So useful in fact that I'm now lost in a sea of emails!"

- "That's what filters and labels are about. It astonishes me how few people like to spend days constructing manual filters to classify email"

Someone adds Bayesian filtering to MUAs/MDAs, classifying mail as (X|NOT X), for interesting values of X. The world rejoices as the intricate filter building interface got reduced to two buttons, and the complexity of classifying email went from O(n) to O(1), and email became manageable again.