trouver le FAI de mon correspondant dans l'entete d'un mail

bonjour,

j'aimerais savoir si "free" est bien le fai de mon correspondant .

un whois de l'IP 81.56.154.52 me renvoi :

inetnum: 81.56.128.0 - 81.56.175.255
netname: FR-PROXAD-ADSL
descr: Proxad / Free SAS
descr: Static pool (IP/ADSL FT)
descr: NCC#2003105812
country: FR
admin-c: ACP23-RIPE
tech-c: TCP8-RIPE
status: ASSIGNED PA
remarks: Spam/Abuse requests: mailto:abuse@proxad.net
mnt-by: PROXAD-MNT
source: RIPE # Filteredinetnum: 212.27.42.0 - 212.27.42.255
netname: FR-PROXAD
descr: Proxad / Free SAS
descr: Server internal infrastructure (mail & news)
descr: Paris, France
country: FR
admin-c: ACP23-RIPE
tech-c: TCP8-RIPE
status: ASSIGNED PA
mnt-by: PROXAD-MNT
source: RIPE # Filtered
remarks: INFRA-AW) by pamc1-f7.hotmail.com with Microsoft SMTPSVC(6.0.3790.211); Mon, 24 Oct 2005 02:03:55 -0700
Received: from son_site (unknown [81.56.154.52])by smtp4-g19.free.fr (Postfix) with ESMTP id 19B823FE37for <mon_adresse@hotmail.fr>; Mon, 24 Oct 2005 11:03:52 +0200 (CEST)
X-Message-Info: JGTYoYF78jFzK+cjWxSoXTg3f2mvq23lE2Yz1Vqejtw=
X-Mailer: Microsoft Office Outlook, Build 11.0.5510
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Return-Path: contact@son_site.fr
X-OriginalArrivalTime: 24 Oct 2005 09:03:55.0615 (UTC) FILETIME=[DCC026F0:01C5D879] [/color]

mais ce qui me douter, c'est que ce mail a été envoyé depuis un site hebergé chez online (donc free)

merci de votre aide