A form returns a Frontpage Server error message instead of posting a confirmation page and sending the form results as an email.
The reason you are receiving the error message is because you are trying to send the form’s information to an email address that is not within your domain name, which Front Page does not allow.
You can still send the mail to the outside address, but you must first create an email alias under your domain name account that aliases mail sent to your outside email address. Then, inside your Front Page form, direct the email to the new alias address you created. When mail hits the alias, it will be redirected to your outside address.