If I send a message from
postfixA -> smartHost postfixB -> smartHost postfixC -> exchange
and only postfixC does MX lookup and it is unable to deliver the message no matter if it is a hard bounce or soft bounce, what does it exactly do ?
Does it look at the header return path and send a message there ? Or does it use envelopeFrom information for it ?
By default, it doesn't let postfixB know in any way, right ? So that if I want to search through logs for what went wrong, I can do it in postfixC only.