You are facing an issue because getmail command will look through only your inbox. You can add a rule in Outlook to move the sent items to a sub-folder , or add a new page in your MAPIEx object. let me tell you how
Open the MAPIEx object and duplicate the page called 'Get Mail', rename the page and the code stage to something else, such as get sent items, then publish it. I did it this way:
Open the code stage and edit this line (line 17) so that it looks like the following, from open inbox to open sent items
Editing the highlighted items is optional but preferable as it makes it easier to debug should there be issues. For instance, you would change anything that says inbox to sent mail.
From there you can call the action from your process just like you would call get mail