Thanks for the heads-up, Spartan_SA.
It’s really a huge issue.
I’ve prepared a workaround, that may be of interest still an official one isn’t available.
Find the following file in your plugins folder: yith-woocommerce-waiting-list/includes/class.yith-wcwtl-email.php
Find the function trigger and edit it.
Comment the line:
$response = $this->send( $users , $this->get_subject(), $this->get_content(), $this->get_headers(), $this->get_attachments() );
Include the following lines (just before or after the previous one):
$headers = $this->get_headers() .'BCC: '. implode(",", $users) . "\r\n";
$response = $this->send( '', $this->get_subject(), $this->get_content(), $headers, $this->get_attachments() );
BCC emails shall be at extra-headers, and must be in a comma-separated-list ended by a “\r\n” sequence.
Cheers.
