Viktor Dukhovni:
>
> > That's easy enough, use sender_dependent_default_transport_maps,
> > and a default transport that returns mail as undeliverable.
> >
> > /etc/postfix/main.cf:
> > sender_dependent_default_transport_maps = hash:/etc/postfix/sender_relay
> > default_transport = error:5.7.1 sender is not authorized
> >
> > /etc/postfix/sender_relay:
> > # sender transport:nexthop
> > us...@example.com smtp:relay-for-user-1.example
> > us...@example.com smtp:relay-for-user-2.example
>
>
> This could perhaps need some additional configuration to be able
> to send bounces. Though if the relay has stringent per sender
> logins (is really an MSA with sender<->login enforcement, not a
> relay MTA), it may not be possible to send bounces. You may
> want to configure working double-bounce delivery, just in case.
Perhaps sender_dependent_default_transport_maps uses the same
null-sender lookup mechanism as other mappings. For example the
transport map has this note:
Note 1: the null recipient address is looked up as
$empty_address_recipient@$myhostname (default: mailer-daemon@hostname).
Wietse
