Guys im setting up a basic email gateway box using Vamsoft Orf to use recipient filtering.
I wanted to turn off the auto-reply email that you get when you send to an invalid address but i dont see an option for this.
So what i did was start playing with the SMTP reponse codes and i notice that if i set it from 550 to 451 the auto-response mails stop coming through, checking this out i see there are split into various ranges.
I was wondering if there is any harm in say me setting the response code to 459 and putting in some custom response text and this way the NDR doesnt seem to come back to the potential spammer?
Although i suppose it would be logged at their server level rather than the client?
The other type of error message is generated by the sending server, when the recipient's server says something like "550: user does not exist" and terminates the SMTP session before the message is delivered. The sender server then sends directly to the sender mailbox a message that says that the recipient could not be reached.
The first type is in principle an email like any other, the other is an internal error message that never leaves the server that generates it.
What is your mail server software?