无法在一个动作中运行一个动作.

Running an action within an action isn't possible, I believe.

如果您查看此操作的代码，则可以访问以下内容:

If you check the code for this action, you have access to the following:

do_action( 'woocommerce_email_before_order_table', $order, $sent_to_admin, $plain_text, $email );

因此，您可能无法挂接到woocommerce_checkout_subscription_created，而只能使用woocommerce_email_before_order_table.

Therefore, you could perhaps NOT hook into woocommerce_checkout_subscription_created and only use woocommerce_email_before_order_table.

然后您可以查询$order是否为订阅，然后相应地修改输出.

You could then query whether or not the $order is a subscription and then modify the output accordingly.

add_action( 'woocommerce_email_before_order_table', function($order, $sent_to_admin, $plain_text, $email) {
    if ( function_exists( 'wcs_order_contains_subscription' ) ) {
        if ( wcs_order_contains_subscription( $order->ID ) ) {
            // Do what you need to do
        }
    } 
}, 10, 4 );