With Exchange 2003 we included features called Smart Forwarding and Smart Reply.
The default behavior with Pocket Outlook is that all forwards from the device will result in the original message being attached in the forwarded message as opposed to remaining in the message body. The concept behind Smart forwarding is that we don't download the original message we allow the user to compose an email and attach the forward as an attachment
The default behavior with Smart Reply is when a user responds to a message we automatically put the previous thread as part of the message. (No attachment)
The question that is often posed is how do we get Smart Forward to behave like Smart Reply. The short answer is you can't. We don't have that functionality in Windows Mobile at this time however I am currently looking for a plug in that may make this possible. In the mean time the work around is to click on edit message right under the message you are typing and then your original message will be sent as part of the body.