Spam represented 88.17% of the total e-mail volume received by large enterprises for November 2007, according to a new report by e-mail security services firm Proofpoint Inc.
The November index fell slightly from October’s index of 89.04%.
According to the report, attachment-based spam grew in November from October levels in image-based spam, PDF spam and Microsoft Word document spam. Image-based spam continued to rise for the second consecutive month to 9.99% of total spam volume during November 2007, up 23.79% from October.
Microsoft Word document spam (.doc attachments) rose by 64.58% over October levels to 4.74% of total spam volume. Microsoft Word document spam in .rtf format also rose during November to represent 0.62% of total spam volume.
PDF spam, while still a very small percentage of total spam volume, rose to its highest levels since September. Its use has increased by 101.15% over October levels, representing 1.75% of total spam volume.
The report also found that MP3 attachments in spam continued to decline since its debut in October. During November, MP3 spam represented just 0.04% of total spam volume, falling by 33.33%.
