Spam Email is a serious problem

Email is a cost effective form of communication both for business and for individual users.  Spam is a term used to refer to unsolicited email, sent by spammers. Spam is a major problem this is evident in the large amounts of spam email that is sent everyday. For example a large ESP (email service provider) such as hotmail can receive up to one billion spam email messages a day. The threat spam email creates can be placed into four main categories: loss in productivity, increased potential to virus attack, reduced bandwidth issues and potential legal exposure. This report will discuss how spam email can be controlled from both an individual and a business perspective. Spam email makes up approximately 80% of email messages received creating a large burden on ESPs and end users worldwide. (Messaging Anti-Abuse Working Group, 2006)

The main method of controlling spam email for both individual users and organisations is through machine learning systems, which can be seen in figure 1.1. Controlling spam is not a static issue spam protection methods must be constantly updated and changed. Most forms of spam protection begin with a filter which separates incoming mail into two folders. The filter operates from learnt memory or a blacklist, the filter puts the mail into the quarantine box if on the blacklist or into the inbox if considered genuine email. If spam mail is placed into the inbox, users have the ability to place the mail onto the blacklist adding to the accuracy of what is regarded as spam. If spam mail does get into the inbox recipients of spam or suspected spam it is important that end users don not open the email and do not click any links. Even if a html link refers to opting out or unsubscribing as this only confirms the email address is ‘alive’ and the spammer will send more nuisance email.

Memory has to constantly keep learning what is ‘good’ and ‘bad’ email. Spammers are not idle whilst machines are learning new ways of fighting against spam must be created. For example more sophisticated learning algorithms which give a weighting for each word in an email message. This allows a new filter to be learnt from scratch in about an hour even when training on more than a million messages. Spammers got around new filters changing the common words such as ‘sex’ and ‘free’ which are regarded as having a heavy weighting and encoding them as HTML ACSII characters ie (fr&#101xe) this allows the user to still see the words but computers can not detect the words and the email is incorrectly classified and placed into the inbox.

Most organisations have internally managed spam filters but spending extra money on spam control by outsourcing email security has many benefits. Spam messages do not simply stop because the 9 till 5 IT staff have gone home. If a new spam threat is identified at night the damage can be done long before IT staff arrive. If organisations join together support can be provided in a much more cost effective manner. Organizations such as the Messaging Anti-Abuse Working Group (MAAWG) have been created to fight against spam focusing on a collaborative effort. MAAWG incorporates major Internet Service Providers (ISP) and network operators worldwide with other associated industry vendors such as google and yahoo. Fighting against spam together allows black lists to monitored, upgraded and maintained just as quickly if not quicker than spammers can create new attacks.

Securing computers with virus and spyware software is a way which spam can be reduced. This minimises the amount of spam email sent using the common technique of creating zombie machine or botnets. Computers which are owned by end-users are infected with viruses or Trojans that give spammers full control of the machine, which are then used to send spam. The spammer’s methods used to send the email is very sophisticated and results in email, even with blocked port 25 (outgoing email port), to be sent out.

Another way spam email can be reduced is disguising email addresses on forums or bulletin boards. This makes it more expensive for a spammer to send emails. As more money is needed to gather valid email addresses. This will help in achieving the goal of making the cost of sending spam email below break even point ie the money gained from sending spam is less than the cost of sending it.

In addition to having spam filtering on a high level end users can create there own personal levels of filtering. The majority of email clients not only have junk mail folders but folder rules can be created which allow email to be sorted into folders specifying words, senders or subject line. This can help keep spam out of sight and become less of a nuisance.