According to email management firm Email Systems, although unsolicited spam email still comprised an average of 75.53 per cent of all email traffic during September, this represents a significant drop from August, when the lowest level of spam at any point was 79.56 per cent and the average more than 85 per cent.
Most noticeably, Email Systems said, the route by which a significant proportion of spam reached the UK appeared to have been directly affected by the extreme weather conditions in the south-eastern United States. In September, the company's monitoring found that spam mainly originated from seven countries - including Korea, France, Canada, Spain, Japan and the US.
Neil Hammerton, managing director of Email Systems said: "The fact that the geographical region which has been devastated by hurricane after hurricane in September coincides with this drop in spam output highlights the fact that a huge proportion of spam email is routed via the US, even though in many cases the email originates from an entirely different part of the world.
"Unfortunately the catastrophe that has struck the region seems not to have deterred spammers too greatly as the last ten days of September saw another significant upturn in the proportion of spam in email, jumping from daily averages of 50 or 60 percent to averages of 80 or 90 percent."
The UK was identified as the worst culprit of spam distribution in September, comprising almost 45 per cent of all unsolicited emails of known origin for the month. However, although a significant and noticeable decrease from recent months, many spammers still managed to distribute their illegal emails - with spam reaching its September peak on Saturday 25 at 93.73 per cent of all email traffic.
The lowest level of spam on any day during September was found to have occurred on Friday 17 September with spam comprising just 54.49 per cent of email. Legitimate mail peaked at 43.03 per cent on the same day, more than double the peak of legitimate mail for the previous month (18.34 per cent).
Sunday 12 September saw the peak of virus traffic at 5.09 per cent - the lowest point of the month came on Sunday 26th September when virus traffic comprised 1.33 per cent of email. The average amount of virus traffic per day was 2.83 per cent, a rise of more than 30 per cent from the August average of 2.16 per cent.