As I understand it the worst thing you can do is reply to them asking them to remove you from their mailing list - it simply confirms that the account is active and so you get flooded with yet more.
If they are completely unsolicited you can contact the ISP of the sender or webmaster whatever.
For example I get a lot that come from yahoo e-mail accounts - with those you forward them to:
abuse@yahoo.com : and the offenders account is closed.
That's the only thing I can suggest.
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Time is an illusion. Lunchtime doubly so.
Epona of The Laughing Hyenas