diff --git a/backup_imap/backup_imap.py b/backup_imap/backup_imap.py
index 354b45c..64fbe5e 100644
--- a/backup_imap/backup_imap.py
+++ b/backup_imap/backup_imap.py
@@ -151,6 +151,7 @@ class BackupImap:
                             with open(message_path, 'wb') as file_pointer:
                                 file_pointer.write(data)
                             self.data['backedup_messages'].append({ "message_id": message_id, "mailbox": mailbox})
+                            self._save_cached_data(self.data)
                         except OSError as error:
                             if error.errno == 36: # File name too long
                                 message_path = os.path.join(
@@ -160,6 +161,7 @@ class BackupImap:
                                 with open(message_path, 'wb') as file_pointer:
                                     file_pointer.write(data)
                                 self.data['backedup_messages'].append({ "message_id": message_id, "mailbox": mailbox})
+                                self._save_cached_data(self.data)
                             else:
                                 self._log.error(
                                     "Error writing email '%s'. %s",