def add_part(part)
      if !body.multipart? && !Utilities.blank?(self.body.decoded)
        @text_part = Mail::Part.new('Content-Type: text/plain;')
        @text_part.body = body.decoded
        self.body << @text_part
        add_multipart_alternate_header
      end
      add_boundary
      self.body << part
    end
def add_part(part)
      if !body.multipart? && !Utilities.blank?(self.body.decoded)
        @text_part = Mail::Part.new('Content-Type: text/plain;')
        @text_part.body = body.decoded
        self.body << @text_part
        add_multipart_alternate_header
      end
      add_boundary
      self.body << part
    end
Adds a part to the parts list or creates the part list