Is there a setting on the MS Exchange Server v6.0.6603.0 that drops the subject line if sending to more than 40 email addresses?

Question

 If I put more than 40 email addresses in the To: field or a combination between the To, To Group, CC or CC Group in Rational Clearquest email notification rule, I get the following and it blanks the Subject field. I have substituted xxxx for server names and ip addresses. This does not occur using a Lotus Notes email server.

Is there a setting on the MS Exchange server that can cause this?

X-MimeOLE: Produced By Microsoft Exchange V6.0.6603.0

Received:  from xxxx.corp.us.xxxx.com ([xxx.xx.xx.xx]) by xxxx.corp.us.xxxx.com with Microsoft xxxx(x.x.xxxx.xxxx); Thu, 20 Apr 2006 16:23:24 -0400

MIME-Version: 1.0

Received:  from localhost ([xxx.xx.xx.xx]) by xxxx.corp.us.xxxx.com with Microsoft xxxx(x.x.xxxx.xxxx); Thu, 20 Apr 2006 16:23:23 -0400

content-class: urn:content-classes:message

Subject:

Date: Thu, 20 Apr 2006 16:23:24 -0400

Message-ID: <[e-mail]>

X-MS-Has-Attach:

X-MS-TNEF-Correlator:

Thread-Index: AcZkuEkZk8YhyKuEQ8OHLLp5OgyQCw==

From: "ClearQuest Admins" <[e-mail]>

Content-Type: multipart/alternative;      boundary="----_=_NextPart_003_01C664B8.46218600"