Ballmer was showing off the Priorities application at the ACM1 conference on the future of computing held by the Association of Computing Machinery in San Diego, California this week.
Using elements such as header structure and the relationship between the recipient and the sender, the system also acts as a spam filter, according to Microsoft researcher Eric Horvitz, who explained that spam mail generally falls to the bottom of the queue.
The system uses the same underlying technology that that is in Microsoft's new Outlook Mobile Manager product (now available in beta).
The difference between this technology and Priorities is that other data input, including hookups to user calendars and even ambient room noise monitors, may be built into the product, to help gauge the end user's circumstances. If the user is in a room where there is a lot of conversation, then the system would know not to send the user e-mail.