I think the issue is you assume the "Favorite" tab is a folder. It isn't. It's a group. The email is saved by default until you delete it. If you want to move it to a different folder then you need to create that folder, but you can't create it in the app. The HTC app only pulls the info from your email account. You need to go to that account (in Yahoo, Outlook, etc.) to add a folder. That folder will sync with the HTC app. If your email client supports it then you can add groups of contacts and label them how you want (Favorites, Family, Coworkers, etc.). If the "Favorite" tab is throwing you off then just don't display it.