On Fri, Dec 21, 2012 at 02:55:39PM +0100, Ignacio Vazquez wrote:
> Just for the record I found a workaround that makes not mandatory
> specifying the remote users. It's a kind of a mixture local/virtual:
> transport_maps = hash:/etc/postfix/transport
> local_recipient_maps = $transport_maps, $virtual_mailbox_maps,
> $alias_maps, $alias_database
>
> /etc/postfix/transport:
> foo...@example.com smtp:172.16.34.34
As I mentioned before, non-default routes without rewriting create
a high risk of routing loops as the non-default destination system
is easily misconfigured to punt the mail back to the MX host.
With rewriting the configurations of the various MTAs involved in
mail routing within an organization can typically share the rewriting
and routing (transport) tables. With explicit selection of a non-local
transport the destination system needs a different routing table
entry that the source system, which makes administration harder.
Finally with Postfix, per-user transport tables are difficult to
scale to thousands of users as moving this a database (LDAP, MySQL,
...) puts the database source in the critical path of the MTA
(transport lookup) where the queue manager cannot schedule deliveries
of messages without a per-recipient remote database lookup. This
can create a performance issue or DoS condition.
Rewriting is safer. Yes, it requires adding internal addresses
in an environment with multiple internal mailstores. Doing that
is a good idea.
--
Viktor.
