The standard behavior of the Outlook Add-In is to attach a short .html file, which can be viewed using any web browser, to your outgoing email messages which contain compressed attachments. This is a short message which describes the benefits of CompreXX and how to obtain it. This message may be inappropriate in some contexts, therefore you may want to disable it.
To disable the extraction message:
Start Outlook.
Under the Tools menu, click Options.
Choose the CompreXX tab.
Uncheck the Include information on how to extract the created attachment file box.