Re: cname resolution

From: Victor Duchovni (no email)
Date: Thu Mar 01 2007 - 08:02:55 EST

  • Next message: Victor Duchovni: "Re: Encryption between mail servers"

    On Thu, Mar 01, 2007 at 07:16:41AM -0500, Wietse Venema wrote:

    > Huaqing Zheng:
    > > 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
    > > @foobar.com's forwarding addresses is stored in LDAP. For example, if
    > > you send mail to , postfix looks up the forwarding
    > > addresses for user in LDAP and returns
    > >
    > >
    > >
    > >
    > > 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
    >
    > /etc/postfix/main.cf:
    > transport_maps = hash:/etc/postfix/transport
    >
    > /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.

    The OP's problem is that not <mumble>.pobox.foobar.com destinations
    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.

    -- 
    	Viktor.
    Disclaimer: off-list followups get on-list replies or get ignored.
    Please do not ignore the "Reply-To" header.
    To unsubscribe from the postfix-users list, visit
    http://www.postfix.org/lists.html or click the link below:
    <mailto:?body=unsubscribe%20postfix-users>
    If my response solves your problem, the best way to thank me is to not
    send an "it worked, thanks" follow-up. If you must respond, please put
    "It worked, thanks" in the "Subject" so I can delete these quickly.
    

  • Next message: Victor Duchovni: "Re: Encryption between mail servers"





    Hosted Email Solutions

    Invaluement Anti-Spam DNSBLs



    Powered By FreeBSD   Powered By FreeBSD