I have some users who received and email containing "document.zip". Unfortunately some claim to have opened it after which receiving a bunch of bounce backs in there inbox (Outlook 2010). No evidence of anything being sent (nothing that matches up in "sent" box). Bunch of their collegues did receive spam and then similar bounce backs. Various tools do not detect anything (Current AVG Bus Edition on PC). VirusTotal.com scan of the orig "document.zip" had a 3/57 detection rate.
Not sure if this is just spam or if something is really going on. Don't seem to be having any other issues at the moment.