Re: cname resolution
- On Thu, Mar 01, 2007 at 07:16:41AM -0500, Wietse Venema wrote:
> Huaqing Zheng:The OP's problem is that not <mumble>.pobox.foobar.com destinations
> > I have a sort of odd dilemma. My company maps user their respective
> > IMAP servers using the CNAME <user>.pobox.foobar.com. The user's
> > @...'s forwarding addresses is stored in LDAP. For example, if
> > you send mail to user@..., postfix looks up the forwarding
> > addresses for user in LDAP and returns
> > user@...
> > user@...
> > This all works and is fine. However, for our mailman server, this is
> > causing some bottlenecks. Since we have lists with thousands of users
> > and each user's forwarding address resolves to
> > <user>@<user>.pobox.foobar.com, postfix is delivering the mail to each
> > user separately, instead of resolving the CNAME
> > <user>.pobox.foobar.com down to one of a dozen real IMAP servers and
> > delivering to multiple recipients on the IMAP server in one shot. Is
> transport_maps = hash:/etc/postfix/transport
> .pobox.foobar.com smtp:pobox.foobar.com
> This will bundle different <user>.pobox.foobar.com deliveries
> in the same mail delivery transaction.
are the same, the logical to physical mapping has a large domain and
small range. The domain is the set of users, the range is the set of
IMAP servers which have per-user CNAME records in DNS. This design
breaks a-priori grouping of users by the "actual" nexthop, requiring
CNAME expansion first, which Postfix will not (and should not) do in
the active queue.
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