forwarded email message gets some headers inserted into body

Giganews Newsgroups
Subject: forwarded email message gets some headers inserted into body
Posted by:  Michael Johnson (architeuthis6…
Date: Thu, 3 Aug 2006

I have written a program in Visual C++ .NET using Indy which POPs messages from a mailbox, appends some extra text to the message (either to the body or to each text message part as appropriate), then forwards the message to a new address. This was working fine for me but at some point--not certain exactly when--I started getting extra stuff in my message parts that look like headers, for example:

This is a multi-part message in MIME format.

Content-Type: text/plain
Content-Transfer-Encoding: binary

Content-Disposition=inline            <--- weird stuff

Test message

Text I appended to a test message

Content-Type: text/html
Content-Transfer-Encoding: binary

Content-Disposition=inline            <--- same thing in html part


Does anyone have any clue what might be causing this? I hesitate to post source code because it's bulky, but suffice to say I have carefully checked and the message part text does not seem to contain this stuff -- it seems to somehow get added by the SMTP Send function.