Thierry Fournier:
> Hi list,
>
> For my own usage I wrote a new DNS filter which is executed by
> smtp / lmtp client before executing DNS request.
>
> It allow to force response on MX requests without performing DNS
> request, or force "domain not found? response.
>
> - For example, I can build MX response to force an email to be
> routed on my own
> servers in place of the real destination serveur. This is useful
> for tests.
>
> - Other example is an easy way to integrate relay on Internet in
> front of existing
> couple of MTA without changing any configuration and keeping
> the high availability provided by the DNS multiple MX records.
> (the ?relay" transport doesn?t seem to allow multiple target).
>
> - Next example is blacklisting specific domain before performing
> the DNS request.
>
> Are you interested by the patch which integrate this functionality
> in main postfix branch ?
Maybe. It depends on whether there are special cases that people
need to know about, such as things that are not supported (dane,
DNSSEC, TLSA) or things that behave in an unexpected way. That is
aside from implementation issues such as hard limits, incomplete
error propagation, portability issues, and so on.
Why inside Postfix, why not in an external DNS proxy?
Why only in the SMTP/LMTP client, why not in a library that could
also be used by other Postfix programs?
Wietse
