diff --git a/data/web/inc/functions.inc.php b/data/web/inc/functions.inc.php
index e5f4f788e..577b52664 100644
--- a/data/web/inc/functions.inc.php
+++ b/data/web/inc/functions.inc.php
@@ -256,6 +256,25 @@ function hasMailboxObjectAccess($username, $role, $object) {
   }
 	return false;
 }
+function hasAliasObjectAccess($username, $role, $object) {
+	global $pdo;
+	if (!filter_var(html_entity_decode(rawurldecode($username)), FILTER_VALIDATE_EMAIL) && !ctype_alnum(str_replace(array('_', '.', '-'), '', $username))) {
+		return false;
+	}
+	if ($role != 'admin' && $role != 'domainadmin' && $role != 'user') {
+		return false;
+	}
+	if ($username == $object) {
+		return true;
+	}
+  $stmt = $pdo->prepare("SELECT `domain` FROM `alias` WHERE `address` = :object");
+  $stmt->execute(array(':object' => $object));
+  $row = $stmt->fetch(PDO::FETCH_ASSOC);
+  if (isset($row['domain']) && hasDomainAccess($username, $role, $row['domain'])) {
+    return true;
+  }
+	return false;
+}
 function pem_to_der($pem_key) {
   // Need to remove BEGIN/END PUBLIC KEY
   $lines = explode("\n", trim($pem_key));
diff --git a/data/web/inc/functions.mailbox.inc.php b/data/web/inc/functions.mailbox.inc.php
index df4344f87..a8d7fef40 100644
--- a/data/web/inc/functions.mailbox.inc.php
+++ b/data/web/inc/functions.mailbox.inc.php
@@ -2119,9 +2119,9 @@ function mailbox($_action, $_type, $_data = null, $_extra = null) {
                     unset($sender_acl_domain_admin[$key]);
                     continue;
                   }
-                  // Check if user has mailbox access (if object is email)
+                  // Check if user has alias access (if object is email)
                   if (filter_var($val, FILTER_VALIDATE_EMAIL)) {
-                    if (!hasMailboxObjectAccess($_SESSION['mailcow_cc_username'], $_SESSION['mailcow_cc_role'], $val)) {
+                    if (!hasAliasObjectAccess($_SESSION['mailcow_cc_username'], $_SESSION['mailcow_cc_role'], $val)) {
                       $_SESSION['return'][] = array(
                         'type' => 'danger',
                         'log' => array(__FUNCTION__, $_action, $_type, $_data_log, $_attr),
@@ -2351,11 +2351,11 @@ function mailbox($_action, $_type, $_data = null, $_extra = null) {
           $stmt->execute(array(':logged_in_as' => $_data));
           $address_rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
           while ($address_row = array_shift($address_rows)) {
-            if (filter_var($address_row['send_as'], FILTER_VALIDATE_EMAIL) && !hasMailboxObjectAccess($_SESSION['mailcow_cc_username'], $_SESSION['mailcow_cc_role'], $address_row['send_as'])) {
+            if (filter_var($address_row['send_as'], FILTER_VALIDATE_EMAIL) && !hasAliasObjectAccess($_SESSION['mailcow_cc_username'], $_SESSION['mailcow_cc_role'], $address_row['send_as'])) {
               $data['sender_acl_addresses']['ro'][] = $address_row['send_as'];
               continue;
             }
-            if (filter_var($address_row['send_as'], FILTER_VALIDATE_EMAIL) && hasMailboxObjectAccess($_SESSION['mailcow_cc_username'], $_SESSION['mailcow_cc_role'], $address_row['send_as'])) {
+            if (filter_var($address_row['send_as'], FILTER_VALIDATE_EMAIL) && hasAliasObjectAccess($_SESSION['mailcow_cc_username'], $_SESSION['mailcow_cc_role'], $address_row['send_as'])) {
               $data['sender_acl_addresses']['rw'][] = $address_row['send_as'];
               continue;
             }
@@ -2398,7 +2398,7 @@ function mailbox($_action, $_type, $_data = null, $_extra = null) {
           ));
           $rows_mbox = $stmt->fetchAll(PDO::FETCH_ASSOC);
           while ($row = array_shift($rows_mbox)) {
-            if (filter_var($row['address'], FILTER_VALIDATE_EMAIL) && hasMailboxObjectAccess($_SESSION['mailcow_cc_username'], $_SESSION['mailcow_cc_role'], $row['address'])) {
+            if (filter_var($row['address'], FILTER_VALIDATE_EMAIL) && hasAliasObjectAccess($_SESSION['mailcow_cc_username'], $_SESSION['mailcow_cc_role'], $row['address'])) {
               $data['sender_acl_addresses']['selectable'][] = $row['address'];
             }
           }
diff --git a/data/web/mta_sts.php b/data/web/mta_sts.php
new file mode 100644
index 000000000..40bfb9e31
--- /dev/null
+++ b/data/web/mta_sts.php
@@ -0,0 +1,18 @@
+<?php
+error_reporting(0);
+header('Content-Type: text/plain');
+
+echo $_SERVER['HTTP_HOST'];
+
+foreach (dns_get_record('mailcow.email', DNS_MX) as $mx_r) {
+  $mx_s[] = $mx_r['target'];
+}
+
+!empty($mx_s) ?: exit();
+
+echo 'version: STSv1' . PHP_EOL;
+echo 'mode: enforce' . PHP_EOL;
+foreach ($mx_s as $mx_r) {
+  printf('mx: %s' . PHP_EOL, $mx_r);
+}
+echo 'max_age: 86400' . PHP_EOL;