DF,

Yes - just like with snail mail you can put any return address into an email with the right email program and a cooperative email server. However what most people don't know is that emails can carry a lot more information about the path they took to get to your inbox.

With Microsoft office outlook and other email programs you can view the email header and in that will be information about the originating email server that sent the message out. That won't tell you who sent it but it will tell you from what provider it was sent. In that header is also a message ID - a unique serial number for that message. If the message was sent from a reputable provider they may be able and willing to track down just where (and who) the message came from. At that point you could initiate legal action.