diff --git a/app/Console/Commands/ParseEml.php b/app/Console/Commands/ParseEml.php
index 7ffd45aba..ee272c666 100644
--- a/app/Console/Commands/ParseEml.php
+++ b/app/Console/Commands/ParseEml.php
@@ -83,6 +83,8 @@ public function handle()
         $this->info($message->getHeader()->raw);
         $this->line('From: ');
         $this->info(json_encode($message->getFrom()[0] ?? [], JSON_UNESCAPED_UNICODE));
+        $this->line('Reply-To: ');
+        $this->info(json_encode($message->getReplyTo()[0] ?? [], JSON_UNESCAPED_UNICODE));
         $this->line('In-Reply-To: ');
         $this->info($message->getInReplyTo());
         $this->line('References: ');
diff --git a/overrides/webklex/php-imap/src/Header.php b/overrides/webklex/php-imap/src/Header.php
index 87aa4ff5f..9a2cd3133 100644
--- a/overrides/webklex/php-imap/src/Header.php
+++ b/overrides/webklex/php-imap/src/Header.php
@@ -241,7 +241,10 @@ public function rfc822_parse_headers($raw_headers) {
             $raw_imap_headers = (array)\imap_rfc822_parse_headers($raw_headers);
             foreach ($raw_imap_headers as $key => $values) {
                 $key = str_replace("-", "_", $key);
-                $imap_headers[$key] = $values;
+                $values = $this->sanitizeHeaderValue($values);
+                if (!is_array($values) || (is_array($values) && count($values))) {
+                    $imap_headers[$key] = $values;
+                }
             }
         }
         $lines = explode("\r\n", preg_replace("/\r\n\s/", ' ', $raw_headers));
@@ -322,12 +325,37 @@ public function rfc822_parse_headers($raw_headers) {
                     }
                     break;
             }
-            $headers[$key] = $value;
+            $value = $this->sanitizeHeaderValue($value);
+            if (!is_array($value) || (is_array($value) && count($value))) {
+                $headers[$key] = $value;
+            } elseif (is_array($value) && !count($value) && isset($headers[$key])) {
+                unset($headers[$key]);
+            }
         }
 
         return (object)array_merge($headers, $imap_headers);
     }
 
+    // https://github.com/freescout-help-desk/freescout/issues/4158
+    public function sanitizeHeaderValue($value)
+    {
+        if (is_array($value)) {
+            foreach ($value as $i => $v) {
+                if (is_object($v)
+                    && isset($v->mailbox)
+                    && ($v->mailbox == '>' || $v->mailbox == 'INVALID_ADDRESS') 
+                    && ((isset($v->host) && ($v->host == '.SYNTAX-ERROR.' || $v->host === null)) || !isset($v->host))
+                ) {
+                    echo 'unset: '.$v->mailbox;
+
+                    unset($value[$i]);
+                }
+            }
+        }
+
+        return $value;
+    }
+
     /**
      * Decode MIME header elements
      * @link https://php.net/manual/en/function.imap-mime-header-decode.php