> On Oct 26, 2016, at 11:53 PM, Bill Cole
> <[email protected]> wrote:
>
> It makes far more sense to implement a truly intentional and permanent block
> based absolutely on the client IP by simply not accepting the connection,
> either in the lower layers of the network or by the MTA simply rejecting the
> connection attempt.
If a domain does not wish to receive email, the
simplest way to achieve that goal is NULLMX:
https://tools.ietf.org/html/rfc7505
example.com. IN MX 0 .
If a particular host does not wish to receive email,
it should not be listed in a domain's MX RRset,
and should refuse connections on port 25.
If a real MTA wants to selectively reject mail it
should do so at "MAIL FROM:", "RCPT TO:", "DATA"
or ".". Rejecting outside a mail transaction is
not reliable.
--
Viktor.
