I have an issue where emails sent out via the SmtpClient class in .NET go directly into the outlook junk mail folder (Outlook 2003 and 2007).

If I send the exact same email (same body, same subject, to and from the same accounts as I use in .NET) from Outlook itself, it will come in fine and not be marked as junk mail.

The only difference is the extra headers that Outlook appends to the email when it is sent directly from Outlook.

I have sort of exhausted my searches in trying to find out how or why this happens and what I can do about it, so I figured I would throw the question out here just to see if anyone may have come across something like this previously.