wp_mail is sending messages with same data

Question

i've a problem with wp_mail() function. It sends me messages correctly but after calling it is sending me multiple messages with the same data, how should I call it properly or kill process to send it only once ?

Here is how i call wp_mail()

        // confirms reservation - doesn't matter for wp_mail()
        $CLASS->ConfirmReservation($data);

        // it gets all updated data about current reservation
        $info = $CLASS->GetReservationInfo($_POST['operation_number'])[0];

        // it prepares me array with parameters: to, subject, msg
        $msgHTML = $CLASS->PrepareOrderHTMLmsg($info);

        // adding headers to array
        $msgHTML['headers'] = array('Content-Type: text/html; charset=UTF-8','From: '.get_bloginfo('name').' <'.get_bloginfo('admin_email').'>');

        // send e-mail
        wp_mail($msgHTML['send_to'], $msgHTML['subject'], $msgHTML['msg'] , $msgHTML['headers']);

Answer 1

From some other page I just send data colected by FORM through simple POST to payments API , and as a respond i get also some POST data for defined url which calls functions from below

function DC_Shortcode(){
        ob_start();
        isset($_POST) ? DotpayCallback() : '';
        return ob_get_clean();
    }
    add_shortcode('DCallback', 'DC_Shortcode');

// DOTPAY
    function DotpayCallback() {
        $CLASS= new CLASS();
        $dotpaySettings = $BOANERGES->getDotpaySettings();


        $PIN = $dotpaySettings[0]['pin_setting'];
        $verify = 1;        //verify data and save, requires valid PIN (above)

        if($verify)
        {
            if($_SERVER['REQUEST_METHOD'] != 'POST') //URLC always uses POST
                die($_SERVER['REQUEST_METHOD']." is incorrect request method");

            if($_SERVER['REMOTE_ADDR'] != '195.150.9.37') //Dotpay IP for URLC is always 195.150.9.37
                die("Unexpected IP: ".$_SERVER['REMOTE_ADDR']);

            if(strlen($_POST['signature']) != '64') //signature always has 64 characters
                die("Invalid POST content");

            $sign=
                $PIN.
                $_POST['id'].
                $_POST['operation_number'].
                $_POST['operation_type'].
                $_POST['operation_status'].
                $_POST['operation_amount'].
                $_POST['operation_currency'].
                $_POST['operation_withdrawal_amount'].
                $_POST['operation_commission_amount'].
                $_POST['operation_original_amount'].
                $_POST['operation_original_currency'].
                $_POST['operation_datetime'].
                $_POST['operation_related_number'].
                $_POST['control'].
                $_POST['description'].
                $_POST['email'].
                $_POST['p_info'].
                $_POST['p_email'].
                $_POST['credit_card_issuer_identification_number'].
                $_POST['credit_card_masked_number'].
                $_POST['credit_card_brand_codename'].
                $_POST['credit_card_brand_code'].
                $_POST['credit_card_id'].
                $_POST['channel'].
                $_POST['channel_country'].
                $_POST['geoip_country'];
            $signature = hash('sha256', $sign);

            if($signature != $_POST['signature']) //compare POST signature with calculated one
                die("Signature mismatch! Expected: ".$signature." Received: ".$_POST['signature']);
        }

        if($_POST['operation_status'] == 'completed') {
            $data = array(
                'id' => $_POST['operation_number'],
                'control' => $_POST['control'],
                'cs' => 1
            );
            // confirms reservation
            $CLASS->ConfirmReservation($data);

            // it gets all updated data about current reservation
            $info = $CLASS->GetReservationInfo($_POST['operation_number'])[0];

            // it prepares me array with parameters to, subject, msg
            $msgHTML = $CLASS->PrepareOrderHTMLmsg($info);

            // adding headers to array
            $headers = array('Content-Type: text/html; charset=UTF-8','From: '.get_bloginfo('name').' <'.get_bloginfo('admin_email').'>');

            // send e-mail
            wp_mail($msgHTML['send_to'], $msgHTML['subject'], $msgHTML['msg'] , $headers);
            wp_die();
            die();
        }

        if($_POST['operation_status'] == 'rejected' || $_POST['operation_status'] == 'fail'){
            $data = array(
                'id' => $_POST['operation_number'],
                'control' => $_POST['control'],
                'cs' => 2
            );
            $CLASS->ConfirmReservation($data);
        }
    }