I REPEAT. Setting the bounce(8) internal service to be handled by a fundamentally incompatible discard(8) delivery agent is wrong, and I hope and expect that nobody on this list will give you any help to misconfigure your system in this way.
> On Sep 26, 2019, at 2:46 AM, feier8097 <ad...@scweixiao.net> wrote: > > Thanks for your suggest again. "bounce unix - - n - 0 discard" is fit for my > own system. I have trouble with how to set it by "postconf.." not "vi > /etc/...". or disable the NDR responses from the system. If on other hand you want actual help to avoid unwanted bounces, you'd be wise to stop asking about how to damage your master.cf file and instead describe how the mail that ultimately bounces enters your system (from authenticated users outbound to remote addresses or external senders inbound to local, but non-existent addresses). You should also provide some configuration information, as described in http://www.postfix.org/DEBUG_README.html#mail -- Viktor.