We are developing our application to be a default e-mail program, and would like it to be one of the options in the Control Panel-> Add or Remove Programs-> Access and Defaults-> Custom-> Choose a default e-mail program: area. How is this done?
It's a rather simple registry change to add the application to the list in IExplore-> Tools -> Internet Options -> Programs -> E-mail: But apparently this is not the list that is displayed in the Access and Defaults area.
Here's the msdn page for Registering Programs with Client Types, which is what you need to do. It's a few registry keys, and there is even a sample for a mail client.