it's just the price of the internet... there's a cheap and easy way of sending messages so people use it. (The actual fishing and sending is more likely to be done by robots than by people.) Actually, it's quite possible that ads for Viagra etc come from genuine trading concerns who do their business online and it's over to you whether to respond. But a lot of junk mail contains viruses etc, so you should never open an attachment from someone you don't know.