diff --git a/include/emailinbox.php b/include/emailinbox.php
index 37b8d4b..2035948 100644
--- a/include/emailinbox.php
+++ b/include/emailinbox.php
@@ -26,7 +26,7 @@ class Emailinbox extends Renderer {
                 $cleanedHeaders[$message->getUid()] = [
                     'title' => $header->subject,
                     'date' => $date,
-                    'unread' => !$flags['Seen'],
+                    'unread' => !isset($flags['seen']) || $flags['seen'] != 'Seen',
                     'from' => $header->from,
                 ];
             } catch (\exception $err) {