The first and foremost need of  any business is a role to perform for its client base, and for the spammer this will typically be the role of advertising products which, due to their unscrupulous nature, could not be advertised via some legal mainstream routine.

Next, the prerequisite for advertising for a product generally includes-

• A source of valid e-mail addresses to send spam mails to.
• A source of delivering email messages in huge numbers to multiple recipients. This is a must for the spammer in spite of the fact that most providers of an Internet connection will not permit the sending of such vast numbers of messages.

The first prerequisite of collecting email addresses is generally fulfilled by a technique known as harvesting. Spammers generally collect email addresses from chat-rooms, newsgroups, web-sites, customer lists and viruses who harvest the user's address books. A practice called 'epending' is also used in which known information is used to get the email address of the receiver. It follows that if we want to put a stop to spam, the only real solution is to block SPAM at the exchange server level, before it can reach the user's mail box. The steps taken in this regard typically include:

• Blacklisting unsecure mail servers.
• Blacklisting compromised computers meant for use at home.
• Checking messages for URLs of known meds-sites and the like.
• Scrutinizing messages for luring features which are typical of bulk-marketing tactics.