On Fri, Jul 24, 2015 at 10:31:10AM +0300, Michael Peter wrote:
http://www.postfix.org/postconf.5.html#reject_unknown_sender_domain
reject_unknown_sender_domain
Reject the request when Postfix is not final destination
for the sender address, and the MAIL FROM domain has 1) no
DNS MX and no DNS A record, or 2) a malformed MX record
such as a record with a zero-length MX hostname (Postfix
version 2.3 and later). The reply is specified with the
unknown_address_reject_code parameter (default: 450),
unknown_address_tempfail_action (default: defer_if_permit),
or 550 (nullmx, Postfix 3.0 and later). See the respective
parameter descriptions for details.
> I am confused that is the meaning "when postfix is not final destination
> for the sender address" ?
The restriction only applies when the domain in question is not
hosted by the receiving Postfix system as determined by its address
class.
http://www.postfix.org/ADDRESS_CLASS_README.html
Sender domains in the local, virtual alias and virtual mailbox
address classes are never rejected by reject_unknown_sender_domain,
they are "known" to Postfix whether or not they are "known" to DNS.
--
Viktor.
