[tlug] mail(): Received (may be forged) question

[Jean-Christian Imbeault <jc@example.com>]

I've just noticed that mail sent from my linux box has this in it's headers:

Received: from localhost.localdomain (ns.tokyo-av-land.com 
[219.118.175.244] (may be forged))
	by ns.mega-bucks.co.jp (8.12.8/8.12.5) with ESMTP id h37298a7013765
	for <jc@example.com>; Mon, 7 Apr 2003 11:09:08 +0900
Received: from www.tokyo-avland.co.jp (localhost.localdomain [127.0.0.1])
	by localhost.localdomain (8.12.8/8.12.8) with ESMTP id h37202tE025219
	for <jc@example.com>; Mon, 7 Apr 2003 11:00:02 +0900
Received: (from apache@example.com)
	by www.tokyo-avland.co.jp (8.12.8/8.12.8/Submit) id h37202Tg025218;
	Mon, 7 Apr 2003 11:00:02 +0900


Why is the mail sent from my box marked as having a possibly forged header?

I have my domain set in /etc/hosts with:

219.118.175.244 www.tokyo-avland.co.jp

and also in /etc/sysconfig/network with:

HOSTNAME=www.tokyo-avland.co.jp
DOMAINNAME=tokyo-avland.co.jp

hostname and dnsdomainname both return the correct values:

# hostname && dnsdomainname
www.tokyo-avland.co.jp
tokyo-avland.co.jp

What is generating the mail header with localhost@example.com and 
ns.tokyo-av-land.com and why those incorrect values?

I've done a dig on ns.tokyo-av-land.com but that comes up empty (as it 
should) so I can't figure out where it comes from.

Can someone offer some hints as to what I should look into in order to 
fix this?

Thanks,

Jean-Christian Imbeault