.WMF exploit

When creating an Office 2007 file (i.e. Word, Powerpoint….etc), an embedded .wmf file is also created. This is causing me grief as our current mail security appliance drops .wmf files. I can easily remove the drop action. However, i do not know whether it is safe to do so or not. Does anyone know if .wmf files are still a major target for exploiting vulnerabilities?

Many thanks.