Thanks Elliot!
I think I found the issue now, the X-Originating-IP tag shows an IP on a block list. Is that something added by the Zimbra web client?
Return-Path:
user1@domain1.com
Received: from host.domain.com (LHLO host.domain.com)
(67.113.20.194) by host.domain.com with LMTP; Tue, 8 Nov 2011
03:31:19 -0800 (PST)
Received: from localhost (localhost [127.0.0.1])
by host.domain.com (Postfix) with ESMTP id 7D477C6BCFD
for <user2@domain1.com>; Tue, 8 Nov 2011 03:31:19 -0800 (PST)
X-Virus-Scanned: amavisd-new at domain.com
X-Spam-Flag: YES
X-Spam-Score: 6.379
X-Spam-Level: ******
X-Spam-Status: Yes, score=6.379 tagged_above=-10 required=6
tests=[BAYES_00=-1.9, HELO_NO_DOMAIN=0.001,
RCVD_IN_BRBL_LASTEXT=1.449, RCVD_IN_PBL=3.335, RCVD_IN_RP_RNBL=1.31,
RCVD_IN_SORBS_DUL=0.001, RDNS_NONE=0.793,
SHORT_HELO_AND_INLINE_IMAGE=1.39] autolearn=no
Received: from host.domain.com ([127.0.0.1])
by localhost (host.domain.com [127.0.0.1]) (amavisd-new, port 10024)
with ESMTP id JYSEHT61WaVf; Tue, 8 Nov 2011 03:31:16 -0800 (PST)
Received: from host.domain.com (localhost [127.0.0.1])
by host.domain.com (Postfix) with ESMTP id 9D520C6BCFC;
Tue, 8 Nov 2011 03:31:16 -0800 (PST)
Date: Tue, 08 Nov 2011 03:31:16 -0800 (PST)
From: user1 <user1@domain1.com>
To: user2 <user2@domain1.com>, XXXXX <XXXXX@yahoo.com>
Subject: Fwd: bills
Message-ID: <3ef785bf-cf31-4bba-82a4-8f998beea5b4@enterprise>
In-Reply-To: <1320725965.41221.YahooMailNeo@web39501.mail.mud.y ahoo.com>
Content-Type: multipart/mixed;
boundary="=_6db2e528-f5b4-4802-9360-9b1266107cc3"
MIME-Version: 1.0
X-Originating-IP: [118.168.111.189]
X-Mailer: Zimbra 7.1.2_GA_3268 (ZimbraWebClient - IE8 (Win)/7.1.2_GA_3268)