I am trying the following, but the output XML is badly formed:

def submit xml = Builder::XmlMarkup.new

xml.instruct!

xml.mail
xml.documents
xml.document
xml.template
xml.source "gallery"
xml.name "Postcard:  Image fill front"

@xml_display = xml      

end

I need it to look more like this:

<?xml version="1.0" encoding="UTF-8"?>
<mail>
  <documents>
    <document>
      <template>
        <source>gallery</source>
        <name>Postcard: Image fill front</name>
      </template>
      <sections>
         <section>
           <name>Text</name>
           <text>Hello, World!</text>
          </section>
       <section>
          <name>Image</name>
          <attachment>...attachment id...</attachment>
          </section>
       </sections>
    </document>
  </documents>
  <addressees>
    <addressee>
      <name>John Doe</name>
      <address>123 Main St</address>
      <city>Anytown</city>
      <state>AZ</state>
      <postal-code>10000</postal-code>
    </addressee>
  </addressees>
</mail>