Oh, boy, this may get interesting! I just received another Klez infected message. And if the sender is the one listed in the return path of the header, it is the secretary of a large group to which I belong. That would mean infected messages went out to everyone in the group. These are mostly middle age and elderly ladies, many who just don't pay much attention to such things as antivirus protection. I'll bet they will be more educated after this!

I called the group secretary, and she already has a friend over there looking at her computer, thinking she might have a virus. So again it really does sound like the return path address might be correct.