There are virus-infected emails going around--lots of them.
They have forged sender names--lots of them.
There are email filters that detect viruses in emails and notify the sender that the email was rejected because of the virus--lots of them.
Therefore, there are delivery failure notice emails being sent to innocent victims of header forging--lots of them.
While the senders of these notices (including Lunarpages and Harvard University) may be well intentioned, their implementation is flawed. Given that most all email addresses on virus-infected emails are forged, they do nothing more than amplify the virus problem