London, Apr 9 : More than 97 percent of all emails sent in the world are unwanted spam, says a Microsoft security report.
According to the report, e-mails are dominated by spam adverts for drugs, and general product pitches.
The global ratio of infected machines was 8.6 for every 1,000 uninfected machines, the study found.
It also found that Office document attachments and PDF files were increasingly being targeted by hackers.