class Mail::FieldList

having to worry about the order they will appear in.
email fields in order. And allows you to insert new fields without
Field List class provides an enhanced array that keeps a list of

def <<( new_field ) 

def <<( new_field )
  current_entry = self.rindex(new_field.name)
  if current_entry
    self.insert((current_entry + 1), new_field)
  else
    insert_idx = -1
    self.each_with_index do |item, idx|
      case item <=> new_field
      when -1
        next
      when 0
        next
      when 1
        insert_idx = idx
        break
      end
    end
    insert(insert_idx, new_field)
  end
end