The number of consumers deleting spam without reading it has climbed to 65 percent from last year's 60 percent. Only 4 percent bother to read spam to see if it is of any use, compared with 5 percent in 2002, and 18 percent the year before, according to a study.

Results of the study, released Monday by DoubleClick, a N.Y.-based provider of tools for the online marketing industry, are based on a survey of 1,000 consumers who use e-mail at least once a week.

Unsolicited e-mail account for a third of the total mail traffic on the internet. Spam-clogged e-mail boxes are creating headaches for system administrators as well as for home users.

But DoubleClick said it is not yet time to write off e-mail as a marketing channel because consumers are accepting legitimate commercial messages in their in-boxes and making purchases based on them.

"The encouraging news from this year's study is that consumers are clearly differentiating between spam and legitimate commercial e-mail," Scott Knoll, vice president of DoubleClick's Marketer Solutions Division, said in a statement.

A majority (91percent) of consumers said they receive special online offers from merchants, retailers and catalogers that they have permitted to send messages. More than 63 percent of respondents said they look at sender's name to distinguish a genuine business offer from spam, an improvement over last year's 59.9 percent.

The study showed that the mention of a discount offer in the subject line entices more people to open such messages and often results in a sale. Sixty five percent of those surveyed made a purchase as a result of an e-mail offer from an online seller or a retail store.

The average volume of e-mail messages per week is rose slightly to 264 from last year's 254, with the ratio of spam (56 percent) unchanged. Doubleclick also said that consumers are using different methods to deal with spam--ranging from using bulk folders to creating alternative e-mail addresses for online buying.