Why do we receive Spam?

Where addresses are published in plain HTML text format on a web site they can be easily ‘harvested’ using automated tools. This has historically been one of the most common methods utilised to build a database of addresses.

E-mail addresses on web sites

When domains are registered on the Internet it is required that contact details are provided and these are published in the Domain Name System (commonly known as DNS) which can be queried by anyone. As with web sites, these addresses can be harvested using automated tools.

E-mail addresses on DNS registration

Many web sites require contact information to be supplied before they will provide information and this can be a source utilised by spammers to obtain valid addresses.

E-mail addresses provided when requesting information

When discussing issues with their peers on Internet newsgroups it is not uncommon for people to provide e-mail address information. In many cases these newsgroups are publicly accessible and addresses can easily be harvested.

E-mail addresses posted in
newsgroups

When an e-mail is sent into an organisation, in most cases it will either be delivered or rejected due to it being an invalid address. The responses to these messages can be utilised by a spammer to build a list of valid addresses within an organisation. To build this list a large number of messages will be sent to standard addresses (using common names such as bob@org.com) and the responses compiled.

Dictionary Attacks/ Directory Harvesting

Infection of a device within an organisation can provide a spammer with a large number of valid addresses by exporting the e-mail address lists from the infected machine and passing this on.

Viruses or Worms