Fix data issues in webapp index (#445)

Author: c-w

opwen_email_server/integration/webapp.py

@@ -227,7 +227,6 @@ def _delete(self, email_address: str, uids: Iterable[str]):
                 continue
 
             self._mailbox_storage.delete(f"{domain}/{email_address}/{folder}/{email['sent_at']}/{uid}")
-            self._email_storage.delete(uid)
 
     def _mark_sent(self, uids: Iterable[str]):
         pass