Worldwide, the spam rate this month was pegged at 89.9 per cent, a drop of 0.8 per cent from the previous month.

In the region, Malaysia and Singapore also saw a drop in the spam rate to 87.7 per cent, and 87.6 per cent respectively, the report added.

"Spam is more commonly sent from computers running Windows than from those running other operating systems," Wood said. "However, spam not identified as coming from botnets was seen in lower proportions coming from Windows machines than from known botnets."