diff --git a/agent/ajax.php b/agent/ajax.php
index 4a37f0e0..0b27f9b8 100644
--- a/agent/ajax.php
+++ b/agent/ajax.php
@@ -46,7 +46,7 @@ if (isset($_GET['certificate_fetch_parse_json_details'])) {
 if (isset($_GET['merge_ticket_get_json_details'])) {
     enforceUserPermission('module_support');
 
-    $merge_into_ticket_number = intval($_GET['merge_into_ticket_number']);
+    $merge_into_ticket_number = intval(preg_replace('/[^0-9]/', '', $_GET['merge_into_ticket_number']));
 
     $sql = mysqli_query($mysqli, "SELECT ticket_id, ticket_number, ticket_prefix, ticket_subject, ticket_priority, ticket_status, ticket_status_name, client_name, contact_name FROM tickets
         LEFT JOIN clients ON ticket_client_id = client_id 
diff --git a/cron/mail_queue.php b/cron/mail_queue.php
index ebedb830..c0098dc4 100644
--- a/cron/mail_queue.php
+++ b/cron/mail_queue.php
@@ -223,9 +223,8 @@ if (mysqli_num_rows($sql_queue) > 0) {
 
         mysqli_query($mysqli, "UPDATE email_queue SET email_status = 1 WHERE email_id = $email_id");
 
-        // Check recipient
-        $domain = sanitizeInput(substr($email_recipient, strpos($email_recipient, '@') + 1));
-        if (!filter_var($email_recipient, FILTER_VALIDATE_EMAIL) || !checkdnsrr($domain, 'MX')) {
+        // Basic recipient syntax check
+        if (!filter_var($email_recipient, FILTER_VALIDATE_EMAIL)) {
             mysqli_query($mysqli, "UPDATE email_queue SET email_status = 2, email_attempts = 99 WHERE email_id = $email_id");
             $email_to_logging = sanitizeInput($email_recipient);
             $email_subject_logging = sanitizeInput($rowq['email_subject']);
@@ -234,6 +233,17 @@ if (mysqli_num_rows($sql_queue) > 0) {
             continue;
         }
 
+        // More intelligent recipient MX check (if not disabled with --no-mx-validation)
+        $domain = sanitizeInput(substr($email_recipient, strpos($email_recipient, '@') + 1));
+        if (!in_array('--no-mx-validation', $argv) && !checkdnsrr($domain, 'MX')) {
+            mysqli_query($mysqli, "UPDATE email_queue SET email_status = 2, email_attempts = 99 WHERE email_id = $email_id");
+            $email_to_logging = sanitizeInput($email_recipient);
+            $email_subject_logging = sanitizeInput($rowq['email_subject']);
+            logApp("Cron-Mail-Queue", "Error", "Failed to send email: $email_id to $email_to_logging due to invalid recipient domain (no MX). Email subject was: $email_subject_logging");
+            appNotify("Mail", "Failed to send email #$email_id to $email_to_logging due to invalid recipient domain (no MX): Email subject was: $email_subject_logging");
+            continue;
+        }
+
         try {
             sendQueueEmail(
                 ($config_smtp_provider ?: 'standard_smtp'),
@@ -275,7 +285,8 @@ if (mysqli_num_rows($sql_queue) > 0) {
 /** =======================================================================
  *  RETRIES: status = 2 (Failed), attempts < 4, wait 30 min
  *  NOTE: Backoff is `email_failed_at <= NOW() - INTERVAL 30 MINUTE`
- * =======================================================================*/
+ * =======================================================================
+ */
 $sql_failed_queue = mysqli_query(
     $mysqli,
     "SELECT * FROM email_queue