>I want to determine the standard email client. How can I do this.
>The reason to find out which client is used is, that I want to use Outlook automation if it is Outlook, in the other case I want to use ShellExecute.

Another way to accomplish this would be to use wwipstuf from www.west-wind.com You don't need to worry about the email client since it sends mail directly to an SMTP server.