Issue
EPL
Volume 84, Number 2, October 2008
Article Number 28004
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
DOI http://dx.doi.org/10.1209/0295-5075/84/28004
Published online 13 October 2008
EPL, 84 (2008) 28004
DOI: 10.1209/0295-5075/84/28004

Correlations and Omori law in spamming

M. Pica Ciamarra1, 2, A. Coniglio2 and L. de Arcangelis1

1   Department of Information Engineering and CNISM, Second University of Naples - 81031 Aversa (CE), Italy, EU
2   Department of Physical Sciences, University of Naples Federico II, INFN and Coherentia - 80126 Napoli, Italy, EU

picaciam@na.infn.it

received 31 July 2008; accepted in final form 12 September 2008; published October 2008
published online 13 October 2008

Abstract
The most costly and annoying characteristic of the e-mail communication system is the large number of unsolicited commercial e-mails, known as spams, that are continuously received. Via the investigation of the statistical properties of the spam delivering intertimes, we show that spams delivered to a given recipient are time correlated: if the intertime between two consecutive spams is small (large), then the next spam will most probably arrive after a small (large) intertime. Spam temporal correlations are reproduced by a numerical model based on the random superposition of spam sequences, each one described by the Omori law. This and other experimental findings suggest that statistical approaches may be used to infer how spammers operate.

PACS
89.75.Da - Systems obeying scaling laws.
89.20.Hh - World Wide Web, Internet.
05.45.Tp - Time series analysis.

© EPLA 2008