Don't send unnecessary ACKs

In some situations, it's not necessary to send an ACK. For example, when
the sender is blacklisted, when the message has no content, or when the
address has ACK sending disabled.

Also it's not necessary to rebroadcast empty messages into a mailing
list.

src/class_objectProcessor.py

@@ -524,7 +524,7 @@ class objectProcessor(threading.Thread):
 
             # Let us now check and see whether our receiving address is
             # behaving as a mailing list
-            if shared.safeConfigGetBoolean(toAddress, 'mailinglist'):
+            if shared.safeConfigGetBoolean(toAddress, 'mailinglist') and messageEncodingType != 0:
                 try:
                     mailingListName = shared.config.get(
                         toAddress, 'mailinglistname')
@@ -567,7 +567,11 @@ class objectProcessor(threading.Thread):
                     toAddress, '[Broadcast subscribers]', fromAddress, subject, message, ackdataForBroadcast)))
                 shared.workerQueue.put(('sendbroadcast', ''))
 
-        if self.ackDataHasAVaildHeader(ackData):
+        # Don't send ACK if invalid, blacklisted senders, invisible messages or disabled
+        if self.ackDataHasAValidHeader(ackData) and \
+            not blockMessage and \
+            messageEncodingType != 0 and \
+            not shared.safeConfigGetBoolean(toAddress, 'dontsendack'):
             shared.checkAndShareObjectWithPeers(ackData[24:])
 
         # Display timing data
@@ -814,7 +818,7 @@ class objectProcessor(threading.Thread):
             address)
         shared.workerQueue.put(('sendmessage', ''))
 
-    def ackDataHasAVaildHeader(self, ackData):
+    def ackDataHasAValidHeader(self, ackData):
         if len(ackData) < shared.Header.size:
             logger.info('The length of ackData is unreasonably short. Not sending ackData.')
             return False