diff --git a/src/lib/utils/utils.php b/src/lib/utils/utils.php
index 7d28e98d..837874db 100644
--- a/src/lib/utils/utils.php
+++ b/src/lib/utils/utils.php
@@ -1265,6 +1265,9 @@ private static function convertRawHeader2Utf8($nonencstr, $utf8str) {
         $str = "";
         $striso2022jp = "";
         foreach (@imap_mime_header_decode($nonencstr) as $val) {
+            if ($val->charset == "unicode-1-1-utf-7") {
+                $val->charset = "utf-7";
+            }
             if (is_null($charset)) {
                 $charset = strtolower($val->charset);
             }