On Sep 26, 2019, at 00:18, feier8097 <ad...@scweixiao.net> wrote: > > The postfix system will return back an email with subject "Undelivered Mail > Returned to Sender"
No, ALL mail servers will do this if they cannot deliver mail they accepted. > But I don't want it send this message. Then do not accept mail you cannot deliver or don’t run a mail server. Swallowing undelivered mail without notifications is an evil best left to companies like Verizon (which has done this in the past).