Why are e-mail messages that have been forwarded, sent as an
attachment (.msg) along with the text still being included
in the body (received on Outlook 2003)?

My iAnywhere Mobile Office 5.7.2010.1216 stopped this
attachment on my iPhone, because it's not supported.

Is it possible stopped on Outlook 2003 client? Have a
specific setting to modify on exchange/outlook 2003 (policy,
format, etc.)?