“Dotted Quad” Spam makes a splashy return to this Report as the volume more than tripled from the month prior. The most observed spam subject line of the month was also the dotted quad spam attack. With respect to message size, attachment spam continued to creep up in volume in March. This, along with an increase in N.D.R. spam, raised the average message size. The 5K.B. – 10K.B. bucket increased by over four percentage points and the 10+K.B. bucket increased by over nine percentage points. With respect to spam categories, scam and phishing messages in April accounted for 17 percent of all spam, remaining un-changed compared to March. Overall, spam made up 89.22 percent of all messages in April, compared with 89.34 percent in March.
Spam and Phishing Landscape - May 2010