You will need to have SMTP server details in order to use UE. A sendmail page is a type of page that you can post a form to and have it email the contents. UE works differently, it writes the code to send an email directly from your page without having to send the info somewhere else. In order to craft the code that sends the email correctly you will need to have the details for an SMTP sever that can be used to send emails. Without these details you will not be able to make use of UE.