Another available program
A shareware program called Skinner 3.1 also puts skins on Outlook Express, as well as several other Windows applications, including, to my surprise, the Control Panel.
They let you try three skins free, but you must register and pay $9.95 to access the rest of their offerings.
When I decided to remove the shareware program, I was able to uninstall it via Control panel, but I had to delete the program from C:\program files manually.
After that I still had the skin on several application windows.
I ran IEmage, selected a skin, applied it, and then deleted it immediately. That removed all the Skinner skins from my windows, and did not install IEmage skins. If you think you want to give Skinner 3.1 a trial, it would be a good idea to also install IEmage so you can get rid of skins you don’t want.