Eugene Podshivalov:
> Assume reject_unverified_sender is set and an email is sent
> From:u...@mydomain.com.
> When the email is sent directly from mail.mydomain.com there is no probe,
> right?
reject_unverified_recipient etc. do not care where mail comes from,
or where it is being sent to.
> But when the message is sent from another server that uses mydomain.com as
> relay then the probe is done, in which case Postfix probes itself.
And it should. If an email address DOMAIN is local, that does not
mean that the MAILBOX will be local. The address can be transformed
with canonical_maps, virtual_alias_maps, it may be routed to a
different system with transport_maps, and it may be aliased with
/etc/aliases to some other local or remote address. Those things
can be 'verified' only by sending a probe message through Postfix.
Wietse
