For the week ending May 20, 2007, Marshal says that image spam accounted for only 15.6 per cent of all spam.
"This is the lowest level we have seen image spam at since mid-July 2006," said Bradley Anstis, Marshal's director of product management.
According to Anstis, last July, image spam accounted for around 13 per cent of all spam.
"Then in October we began to see dramatic increases in the volume and consistency of image spam. Image spam rose to become the dominant form of spam in the first quarter of this year, often exceeding 40 per cent of all spam," he said.
"We recorded a peak level of 56.1 per cent image spam in January. However, image spam has been on the decline for the past two months and is now back to its mid-2006 levels," he added.
Anstis went on to say that it is difficult to say if this latest trend marks the end of image-based spam, but it is, he said, worth noting that the anti-spam community has caught up with image spam to a large extent.
Don't relax too much though, as Anstis thinks that the downturn in image-based spam may mark a return by spammers to the more traditional forms of text-based spam...