return new WP_Error(
				'woocommerce_rest_email_preview_not_rendered',
				__( 'There was an error rendering an email preview.', 'woocommerce' ),
				array( 'status' => 500 )
			);
		}
		ob_end_clean();
		$email_subject = $this->email_preview->get_subject();
		$email         = new \WC_Emails();
		$sent          = $email->send( $email_address, $email_subject, $email_content );

		if ( $sent ) {
			return array(
				// translators: %s: Email address.
				'message' => sprintf( __( 'Test email sent to %s.', 'woocommerce' ), $email_address ),
			);
		}
		return new WP_Error(
			'woocommerce_rest_email_preview_not_sent',
			__( 'Error sending test email. Please try again.', 'woocommerce' ),
			array( 'status' => 500 )
		);
	}

	/**
	 * Handle the POST /settings/email/save-transient.
	 *
	 * @param WP_REST_Request $request The received request.
	 * @return array|WP_Error Request response or an error.
	 */
	public function save_transient( WP_REST_Request $request ) {
		$key    = $request->get_param( 'key' );
		$value  = $request->get_param( 'value' );
		$is_set = set_transient( $key, $value, HOUR_IN_SECONDS );
		if ( ! $is_set ) {
			return new WP_Error(
				'woocommerce_rest_transient_not_set',
				__( 'Error saving transient. Please try again.', 'woocommerce' ),
				array( 'status' => 500 )
			);
		}
		return array(
			// translators: %s: Email settings color key, e.g., "woocommerce_email_base_color".
			'message' => sprintf( __( 'Transient saved for key %s.', 'woocommerce' ), $key ),
		);
	}
}