Yahoo researchers have found what may be another way to identify (and block) spammers. Spammers are hard to identify, with their constant changes of domains and IP addresses and euphemisms (or code) to disguise unacceptable words. Any new way to block them might more profitably come from studying the habits of frequent email users.

Between 80 and 90 percent of all email in the world is spam, so even a small edge in the constant gobbling of bandwidth, storage space, and time is a definite advantage.

Researchers focused on frequent users of email: when were they sending emails, how frequently, and when email sessions began and ended.

The email users fell, surprisingly, into two distinct categories: those who sent most of their email during the working day (larks) and those users who sent email starting in the mid-morning and continuing late into the night (owls). The data did not present a continuum, as might have been expected, but two well-defined categories.

Another finding, not surprising at all, given the fact that most humans are creatures of habit, was that the email behavior was stable for each individual, for the most part, over a period of two years. This stability allows an email service to recognize the high probability that an account is being hijacked for nefarious purposes when a sudden spike in the volume of email doesn't match the pre-established pattern. The spambot can be targeted and the user alerted or the account frozen.

The dark side of this data is that websites can use it to tailor their services (read: advertising) to individuals, even perhaps to look at patterns of visits to websites to discern users' preferences and the probability of their being interested in similar ones.

Another use for the research could be to allow heavy usage sites, such as Twitter, which depend on real-time interactions, to optimize how their servers allocate resources.

Lots of opportunity here for useful applications--and misuse of data.