Pipelining with SMTPDeliveryAgent Not Handling "530 5.7.1" Response

[bm3780]

NOTE: This issue was encountered while using the Netty 4.x branch.

I encountered a problem while using SMTPDeliveryAgent with a configuration of PipeliningMode.TRY. Our exchange mail server has a whitelist of allowed IPs, and if not allowed the server responds to EHLO request with a "530 5.7.1 Client was not authenticated" response. In my development environment, I encountered this scenario and was surprised that the SMTPClientFuture never completed. This problem is specific to PIPELINING as when I use PipeliningMode.NO, everything works OK and the future is completed.

I think I have tracked down the issue to be within the NettySMTPClientSession#addCollectionFutureHandler, where if a 530 is encountered (which short-circuits the other expected responses from RCPT, DATA, etc), the expected 'responsesCount' is never reached and thus never removes itself from the pipeline.

[normanmaurer]

@bm3780 thanks for reporting... will try to check today.