The email template used by default will generate a nice html email.
You can modify it to your own liking by editing the files email.htt and email_field_value.htt files in the template subdirectory.
This file has the body of the email that will be sent.
You can use the main output fields as described in the
Basic structure page, including one special field called {HEADER}.
This header field is also used the the forms with the name "header".
The standard email is created with tables to make sure it will behave correctly in all email clients and webmail interfaces, but you are free to change the layout to your liking.
The most important field is the field {MAILMESSAGE} wich is created by the template file email_field_value.htt, once for each field.
This file is used for each field in the form and will only output {FIELD} and {VALUE} per fieldname in your form.