Email Header for Outlook Flag for Follow Up? [RESOLVED]

Is there an email header that can set the Flag for Follow Up action in MS Outlook?

For instance, I can set the X-Priority header and get the red exclamation point in MS Outlook.

I don't know what is the most appropriate forum for this post. (VBA, n-tier)
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[RequestReclassification /]

Hey, these tags don't work ;)

The following headers seem to be sufficient:

Reply-By: Thu, 3 Feb 2005 00:00:00 -0600
X-Message-Flag: Follow up