D G Teed:
> In your opinion. In our practical situation, it would be a benefit
> if there was flexibility, and we could decide how postfix
> treats "no DNS reply".
In my real-world experience, there are brief network outages all
the time. It would be really bad if all mail were returned as
undeliverable, just because some router was clogged up for a minute.
As discussed on this list, you can configure Postfix to make
exceptions for specific domains. However it is a mistake to handle
"no DNS reply" as "host does not exist" for the general case.
Wietse