Four in five e-mail messages are spam, and nearly a quarter of those advertise goods and services, according to Symantec Corp.

The Cupertino, Calif.-based vendor this week released its May spam update, which tracks the percentage of e-mails that are spam.

The categories of spam are tracked by the Symantec probe network, and classifies them as either product, adult, financial, scams, health, fraud, leisure, political The top three categories were product, financial and Internet.

Seventeen per cent were financial, advertising services such as investments, credit reports, loans or real estate. Sixteen per cent of messages were classified as Internet, meaning they advertise services such as Web hosting, Web design or spamware.

One recent trend is spammers to take advantage of the “I feel lucky” option of Google’s search engine by directing users to a spoof Web site

In April, Symantec observed an increase in non-delivery report messages sent in response to spam but in May this decreased to two per cent.