I have found out the following regarding an issue I am having with an Edit This Task button for Sharepoint in Outlook 2007.
You will need to check with your Exchange Server administrator and make sure the following X-Headers are not being stripped or blocked.
X-Sharing-WSSBaseUrl
X-AlertWebSoap
X-Sharing-ItemID
X-Sharing-Remote-Uid
X-Sharing-Config-Url
X-AlertServerType
X-AlertWebUrl
X-AlertId
X-AlertTitle
X-Sharing-Title
I have looked at http://gsexdev.blogspot.com/2004/08/using-x-headers-with-exchange.html and it makes no sense to me.
I don't know how to check this out, does anyone have any ideas?