In late June 2007, spammers engaged in new spam campaigns in which they embedded messages within PDF documents. By using PDF files, spammers attempted to bypass text and image scanning engines in email security products. Because these PDF attacks utilized existing botnets to generate similar traffic patterns on the Internet as more traditional spam attacks. Spamjadoo Greylist antispam mode is now integrated with PDF spam block engine and has the capability to block such spam without even analyzing the content of it. Thanks to ESP technology for achieving this kind of blocking first time in the world.

Spamjadoo antispam research team detected at least two forms of the PDF spam campaigns: 1) full documents resembling investment analyst reports of reputable firms, and 2) image-only PDF files resembling the image spam attacks introduced in 2006. Spamjadoo ESP technology allows blocking PDF spam without analyzing the content, and still ensuring ZERO chance of lossing the desired and important email.