Spammers use a technique called Email Harvesting, which is the collecting of email addresses in bulk. The purpose behind this is to use it for spamming or sending bulk emails. Spammers usually collect a large list of email addresses and use it for posting bulk advertisements. With the large numbers involved, Email Addressing Harvesting programs are now available to make the process automatic. Usually, a spambot or spyware is used for searching on websites, email addresses in email messages, or in the address books of infected users. These are then added to a database and sold to spammers, who then send spam ads to all the harvested email addresses.