public function getBody()
	{
		$number		= count( $this->parts );
		if( !$number )
			return '';

		$innerBoundary	= $this->mimeBoundary.'-1';

		$contents	= array( 'This is a multi-part message in MIME format.');
		$contents[]	= '--'.$this->mimeBoundary;
		$contents[]	= 'Content-Type: multipart/alternative;';
		$contents[]	= ' boundary="'.$innerBoundary.'"'.Net_Mail::$delimiter;
		foreach( $this->parts as $part )
			if( $part instanceof Net_Mail_Body )
				$contents[]	= '--'.$innerBoundary.Net_Mail::$delimiter.$part->render();
		$contents[]	= '--'.$innerBoundary.'--'.Net_Mail::$delimiter;

		foreach( $this->parts as $part )
			if( $part instanceof Net_Mail_Attachment )
				$contents[]	= '--'.$this->mimeBoundary.Net_Mail::$delimiter.$part->render();
		$contents[]	= '--'.$this->mimeBoundary.'--'.Net_Mail::$delimiter;
		return join( Net_Mail::$delimiter, $contents );
	}