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postfix-users: Re: Aliases LDAP maps from the MX ?

Re: Aliases LDAP maps from the MX ?

From: Victor Duchovni <Victor.Duchovni_at_nospam>
Date: Fri Oct 08 2010 - 17:00:29 GMT
To: Postfix users <>

On Fri, Oct 08, 2010 at 12:50:42PM -0400, Wietse Venema wrote:

> Victor Duchovni:
> > I avoid the need for such empty relay tables, by making all my
> > externally-facing domains (the domains in which users get their
> > primary email addresses) be virtual alias domains. All internal
> > delivery is to "mailbox" domains that are the result of virtual
> > alias rewrites:
> >
> >
> > virtual_alias_domains =
> >
> > indexed = ${default_database_type}:${config_directory}/
> > virtual_alias_maps = ${indexed}virtual
> > transport_maps = ${indexed}transport
> >
> > virtual:
> >
> ...
> That is simpler, but I tried to avoid this, because sometimes the
> back-end MTA is configured to accept but not

In many business email systems, the back-end store is MSFT Exchange,
in which case, support for non-primary addresses is not difficult,
one just populates the mailbox addresses into


one also makes the Exchange servers authoritative for the
"" domain, but forward anything unresolved int the
parent domain ( to the cross-domain mail hub for routing.

This is most useful when multiple mail store environments are present.
(Multiple Exchange installations, and/or other non MSFT mailstores).

Some people find it easier to rewrite mailbox->primary mail in
smtp_generic_maps, so that the backend servers still see the primary
address, but the Postfix queue sees mailbox domains, and thereby avoid
per-user transport lookups, which typically involve much slower
(compared to indexed-file lookups) LDAP or SQL queries and can adversely
impact queue manager performance.

-- Viktor.