Do you have Digital File Pro or any previous versions of Universal Email installed? You will need to ensure that you completely uninstall any previous versions of these extensions before installing UE 4.
When you add the 'create email message' server behavior and choose to create a file and select from one of the styles it will use this file for the body of the message. The code in this file will take all of the posted values from your form and list them out one at a time. You should check to ensure that you have all of the other versions uninstalled, then run a simple test with a small form on the page that has the method set to post and the action blank. When you add in the Universal Email server behavior make sure that the trigger is set to button pressed then test out the form. You should receive an email with the values entered into the form.