Add custom control outside Outlok ribbon

Question

I'm new to develop Outlook add-in. I want to write a custom attach file service. When user select attached files, my add-in will upload these files to my server. I want to show a control display upload progress. And I want put this control in same position with original attach file control.

My problem is, I cannot find any document about adding a control outside the Outlook robbin. Most documents guide me to add control to robbin, or a new tab. See this picture below. I want to put my control in red rectangle position, or below the Subject field.

Is it possible to do? Thanks.

Answer 1

I'd love some insight on how to accomplish this as well. I've been wanting to do something similar in Word.