Don't accept replies from unidentifiable sources

inbox.py

@@ -214,7 +214,10 @@ def savePostToInboxQueue(baseDir: str,httpPrefix: str, \
                     if replyNickname and replyDomain:
                         if isBlocked(baseDir,nickname,domain,replyNickname,replyDomain):
                             print('WARN: post contains reply to a blocked account: '+replyNickname+'@'+replyDomain)
-                            return None                        
+                            return None
+                    else:
+                        print('WARN: post is a reply to an unidentified account: '+postJsonObject['object']['inReplyTo'])
+                        return None
             if postJsonObject['object'].get('content'):
                 if isinstance(postJsonObject['object']['content'], str):
                     if isFiltered(baseDir,nickname,domain,postJsonObject['object']['content']):