> On Feb 11, 2021, at 6:29 PM, Eugene Podshivalov <yauge...@gmail.com> wrote:
>
> Assume reject_unverified_sender is set and an email is sent
> From:u...@mydomain.com.
This is an smtpd(8)/access(5) feature, and so only applies when email is
received via SMTP and the restriction in question is applied to the message,
(i.e. is not short-circuited by some earlier "OK" action). It cannot apply
when email is submitted locally via sendmail(1)/postdrop(1).
> When the email is sent directly from mail.mydomain.com there is no probe,
> right?
See above.
> 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.
Probes verify whether an input address is plausibly valid by simulating
delivery. The recipient is handed off to some transport, which reports
success ("deliverable") or failure. There's no distinction here between
local and remote transports.
--
Viktor.
