Why is spam a problem?

It slows down network traffic and takes up storage space. It can expose you to email borne virus and malware infections causing your computer to actually become a source of spam and denial of service attacks. It can expose you to frauds and scams such as phishing attacks and "419" Nigerian fraud type scams. These scams can target your wallet, your online (bank) accounts, your social security number and other private information. it causes a loss in productivity, both in removing unwanted messages from your inbox and suffering the loss of incorrectly filtered email. It's just downright irritating to have to deal with.