Even if you “uninstall” Outlook Express via Add/Remove Windows Components (type
control appwiz.cpl,,2 at the command prompt), it is still very much installed. The icons and shortcuts pointing to it are gone but you can still easily launch Outlook Express by typing msimn at the command line.
More info here: OLEXP: Command Line Options for Outlook Express
Also, the site to go to for everything Outlook Express: Inside Outlook Express