it, and also on the extent to which the person is willing to
tolerate a disturbance at that particular moment, which
itself depends on the task in which the person is engaged.
Contextual information can also be used to make a
decision about how relevant the email is, from that person’s
calendar, from audio and video sensors which monitor the
person’s focus of attention, and from log files of past user
behaviour. Of course, this is for more advanced needs;
machine-learning is also used to filter out the much more
commonplace and vexing volumes of spam that increasingly
assault our mailboxes.