public function setEmail($email)
	{
		if ( $email == $this->getEmail() ) { return; }

		if( $email !== '' && preg_match('/^.+@[a-zA-Z0-9\-]+(\.[a-zA-Z0-9\-]+)*$/', $email) !== 1 ) {
			throw new MShop_Exception( sprintf( 'Invalid characters in email address: "%1$s"', $email ) );
		}

		$this->_values['email'] = (string) $email;
		$this->setModified();
	}