It is designed to prevent non-pre-authorized machine-generated mail, because
 that is the kind that can consume our time without also consuming that of
 the person sending the message. I'm dying, as is everyone in this room, at
 the rate of one second per second. [counter]. We all have about 2.5e9
 seconds, one metric lifetime, and anything which uses that time without our
 permission had better have a good reason for doing so.

 Anything or anyone that seeks to get my attention is consuming my time.
 Deleting the spam from my inbox requires me to evaluate the message, based
 just upon the subject and apparent sender.