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filter is not described

woocommerce_mail_callback filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_mail_callback', 'filter_function_name_6992', 10, 2 );
function filter_function_name_6992( $string, $that ){
	// filter...

	return $string;
}
$string
-
$that
-

Where the hook is called

WC_Email::send()
woocommerce_mail_callback
woocommerce/includes/emails/class-wc-email.php 653
$mail_callback        = apply_filters( 'woocommerce_mail_callback', 'wp_mail', $this );

Where in WP core the hook is used WooCommerce

Usage not found.