Plugin sends plaintext password

Hi I really also want to know how I can change the plugin to just send the default Welcome Email to the user when he is approved, where the user gets to pick an own password.

I tried doing it but it doesn’t work. I added this in the functions.php:

// modify the default registration message
function send_welcome_mail() {
 wp_new_user_notification( $user_id, $deprecated, $notify = 'both');
}

add_filter( 'new_user_approve_approve_user_message_default', 'send_welcome_mail' );

I am using the hook that is provided by this plugin, but the default mail is not sent.
How can I achieve that?

Best,

Jonas

Did you find out how to modify the approval e-mail?