In recent years, there has been considerable interest among people to use short message service (SMS) as one of the essential and straightforward communications services on mobile devices. The increased popularity of this service also increased the number of mobile devices attacks such as SMS spam messages. SMS spam messages constitute a real problem to mobile subscribers; this worries telecomm...

A frequently proposed method of reducing unsolicited bulk email (“spam”) is for senders to pay for each email they send. Proof-ofwork schemes avoid charging real money by requiring senders to demonstrate that they have expended processing time in solving a cryptographic puzzle. We consider how difficult that puzzle should be so as to be effective in preventing spam. We analyse this both from an...

Over the last decade spam has become a serious problem to email-users all over the world. Most of the daily email-traffic consists of this unwanted spam. There are various methods that have been proposed to fight spam, from IP-based blocking to filtering incoming email-messages. However it seems that it is impossible to overcome this problem as the number of email-messages that are considered s...

Unsolicited Commercial Email (UCE), or Spam, is nowadays an increasingly serious problem to email users. A number of anti-spam schemes have been proposed in the literature and some of them have been deployed in email systems, but the problem has not been well addressed. One of those schemes is challenge-response, in which a challenge, ranging from a simple mathematical problem to a hard-AI prob...

We provide an automated graph theoretic method for identifying individual users’ trusted networks of friends in cyberspace. We routinely use our social networks to judge the trustworthiness of outsiders, i.e., to decide where to buy our next car, or to find a good mechanic for it. In this work, we show that an email user may similarly use his email network, constructed solely from sender and re...

Email spam or junk e-mail (unwanted e-mail “usually of a commercial nature sent out in bulk”) is one of the major issue of the today's Internet, that cause financial damage to companies and annoying individual users. Among the approaches developed to stop spam, filtering is an important and popular one. Common uses for mail filters include organizing incoming email and removal of spam and compu...

During the last decade the number of spam messages sent has increased significantly. These undesired emails place a heavy burden on end users and email service providers. As a result, a tenacious struggle to outsmart each other exists between people who send spam and the spam filter providers. Constant innovation is therefore of vital importance to curb the rapid increase of spam. In this artic...

We present ErDOS, an Early Detection scheme for Outgoing Spam. The detection approach implemented by ErDOS combines content-based detection and features based on inter-account communication patterns. We define new account features, based on the ratio between the numbers of sent and received emails and on the distribution of emails received from different accounts. Our empirical evaluation of Er...