After hitting the "Send Registered" button, the features available using the Outlook Desktop plug-in will be displayed in a pop-up window. Once you have set the desired options for your message,  hitting the "Send" button in the Feature window will cause your email to actually be sent. 

The Outlook Desktop Features pop-up window looks like this.  

For a general overview of these Features, please refer to the article in the RMail 101 section RMail -Features at a glance

For more detailed information on each individual feature please refer to the next article in this section Outlook Desktop - Available Features