If you use Windows and Internet Explorer, you can run a One Click Fix that lets you define your default email client (including Outlook Express).
Set Outlook Express as the Default Email Client
- Open Outlook Express and select Tools from the top menu, then Options from the dropdown list.
- On the bottom of the General tab, click the button titled Make Default next to This application is not the default Mail handler.
- Click OK to return to Outlook Express. If you click on an email address link, Outlook Express will now be the program that opens.