maybe something like
$query = mysql_query("SELECT email_address, password FROM your_table");
$subject = "Your Password";
$headers = "From: [email]admin@yourdomain.com[/email]";
while($row = mysql_fetch_array($query)) {
$to = $row["email_address"];
$msg = "Your password is " . $row["password"];
mail($to, $subject, $msg, $headers);
}
Cgraz