Sometimes people want to mark messages in Outlook as Do Not Archive. This functionality exists in the Enterprise Vault Outlook Addin. Here is what you can do :
Firstly you have to be using the full client, not the HTTP client. Note: I have not tried DCOMOverrideRPCHTTP.
If you use the full client, you get to the “Do Not Archive” checkbox as follows, depending on your Outlook version :
Open the item, by double clicking on it.
Click on the Office symbol at the top left of the item :
And then click on Properties
Lastly you’ll see the checkbox, on the Enterprise Vault tab :
You get to the same dialog by opening the item, and clicking on File then Properties.