[RndTbl] Wrong Address E mail

[author]

 I got an e-mail today addressed to someone else.
It was aimed at someone with a  @hotmail  account.
I don't have a @hotmail account.
The e-mail had an address totally different from mine,
but I ended up with it.  Advertising for some wretched
diet scheme.
  Why would an ISP send one of its clients e-mail
not addressed to that client ?
 Is it a server problem or the client's mail software?
Or perhaps, internet voodo?