Filtering PDF-/XLS-/Image-Spam With ClamAV (And ISPConfig) On Debian/Ubuntu

There is currently a lot of spam where the spam information is attached as .pdf or .xls files, sometime also hidden inside a .zip file. While these spam mails are not easy to catch with e.g. SpamAssassin or a Bayes filter, the ClamAV virus scanner can catch them easily when it is fed with the correct signatures as ClamAV is built to scan mail attachments. http://www.howtoforge.com/ispconfig_sanesecurity_clamav_debian_ubuntu