Fix so ANY record is not used for email domain validation, use A, MX, CNAME, AAAA instead (#6581)

CHANGELOG

@@ -5,6 +5,7 @@ CHANGELOG Roundcube Webmail
 - Fix handling of empty entries in vCard import (#6564)
 - Fix bug in parsing some IMAP command responses that include unsolicited replies (#6577)
 - Fix PHP 7.2 compatibility in debug_logger plugin (#6586)
+- Fix so ANY record is not used for email domain validation, use A, MX, CNAME, AAAA instead (#6581)
 
 RELEASE 1.3.8
 -------------

program/lib/Roundcube/rcube_utils.php

@@ -119,18 +119,16 @@ class rcube_utils
 
             $rcube = rcube::get_instance();
 
-            if (!$dns_check || !$rcube->config->get('email_dns_check')) {
+            if (!$dns_check || !function_exists('checkdnsrr') || !$rcube->config->get('email_dns_check')) {
                 return true;
             }
 
-            // find MX record(s)
-            if (!function_exists('getmxrr') || getmxrr($domain_part, $mx_records)) {
-                return true;
-            }
-
-            // find any DNS record
-            if (!function_exists('checkdnsrr') || checkdnsrr($domain_part, 'ANY')) {
-                return true;
+            // Check DNS record(s)
+            // Note: We can't use ANY (#6581)
+            foreach (array('A', 'MX', 'CNAME', 'AAAA') as $type) {
+                if (checkdnsrr($domain_part, $type)) {
+                    return true;
+                }
             }
         }