The remote host is missing an update to gdk-pixbuf announced via advisory DSA 464-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20464-1

Thomas Kristensen discovered a vulnerability in gdk-pixbuf (binary package libgdk-pixbuf2), the GdkPixBuf image library for Gtk, that can cause the surrounding application to crash. To exploit this problem, a remote attacker could send a carefully-crafted BMP file via mail, which would cause e.g. Evolution to crash but is probably not limited to Evolution. For the stable distribution (woody) this problem has been fixed in version 0.17.0-2woody1. For the unstable distribution (sid) this problem has been fixed in version 0.22.0-3. We recommend that you upgrade your libgdk-pixbuf2 package.