This is a basic idea
$conn=mysql_connect("localhost", "user", "pasword);
$db=mysql_select_db("your database", $conn);
$sql="SELECT email FROM your_table";
$result=mysql_query($sql, $conn);
while($res=mysql_fetch_array($result))
{
mail("$res["email"]", $subject, $message);
}
That's it. Make sure that you have mail aggent such as qmail or sendmail setup, otherwise it won't send.
If you want to setup small mailing list, than check this link:
http://www.thickbook.com/extra/php_sublist.phtml
Di