Customer receives 5.7.1 smtp; 554 5.7.1 This message has been blocked because the HELO/EHLO domain is invalid.

I am running exchange 2013 have a customer is trying to send us an email from mail server at Domain1 as a user in Domain2 gets the following error:

Can we change a setting in Exchange to allow mail from mismatched domains Domain1- Domain2 to be allowed and not rejected

#5.7.1 smtp; 554 5.7.1 This message has been blocked because the HELO/EHLO domain is invalid.> #SMTP#

Received: from zixvpm01.Domain1.org (ZixVPM [127.0.0.1])

        by Outbound.Domain1.org (Proprietary) with ESMTP id 597351D012B

        for <MM@MyDomain.com>; Thu,  9 Oct 2014 08:51:48 -0500 (CDT)

Received: from CHSEXCH-2.Domain1.org (chsexch-2.Domain1.org [10.16.4.137])

        by zixvpm01.Domain1.org (Proprietary) with ESMTP id E32A71D8042

        for <MM@MyDomain.com>; Thu,  9 Oct 2014 08:51:47 -0500 (CDT)

Received: from CHSEXCH-1.Domain1.org ([169.254.5.235]) by

 CHSEXCH-2.Domain1.org ([10.16.4.137]) with mapi id 14.01.0355.002; Thu, 9

 Oct 2014 08:51:47 -0500

From: "Sickley, Duke" <DSickley@Domain2.org>

To: "MM@MyDomain.com" <MM@MyDomain.com>

Subject: test email

Thread-Topic: test email

Thread-Index: Ac/jyAugBvH/hzCURGOnyc2QAnIFnA==

Date: Thu, 9 Oct 2014 13:51:46 +0000

Message-ID: <849999A84573204CA4278D68AE7C25DD014E975300@CHSEXCH-1.Domain1.org>

Accept-Language: en-US

Content-Language: en-US

X-MS-Has-Attach:

X-MS-TNEF-Correlator:

x-originating-ip: [10.80.10.52]

Content-Type: text/plain; charset="Windows-1252"

Content-Transfer-Encoding: quoted-printable

MIME-Version: 1.0