Re: virtual_alias_maps: rewriting outbound

From: Chris McKeever (no email)
Date: Sun Jul 02 2006 - 16:08:22 EDT

  • Next message: Magnus Bäck: "Re: local_recipient_maps and backup mx"

    alright - I think I understand where this is failing -
    let me give this a go here -

    thanks

    On 7/2/06, mouss <> wrote:
    > Chris McKeever wrote:
    > > On 7/2/06, Magnus Bäck <> wrote:
    > >> On Sunday, July 02, 2006 at 20:35 CEST,
    > >> Chris McKeever <> wrote:
    > >>
    > >> > On 7/2/06, Magnus Bäck <> wrote:
    > >> >
    > >> > > But you don't want bounces. Bounces are bad. You want rejections. It
    > >> > > is true that virtual alias rewriting is performed recursively -- but
    > >> > > the recipient validation made by smtpd(8) is NOT recursive. If a
    > >> > > lookup returns a result, the address it valid. This means that your
    > >> > > Postfix will accept any address with a dot in it, e.g.
    > >> > > , and later bounce the invalid recipient
    > >> > > .
    > >
    > >>
    > >> What server produces this bounce? Without that information the
    > >> above bounce message snippet is utterly and completely useless.
    > >>
    > >> Never show bounce messages. Always show logs from your server.
    > >>
    > >
    > > Magnus - thanks for helping me through this:
    > >
    > > both messages are coming from the same server, here are the logs - one
    > > sent with the 'dot' format and one without - both generate the same
    > > unknown user log message
    > >
    > > Jul 2 14:18:00 prupref-mailgate postfix/virtual[28097]: F0F07C8EBE:
    > > to=<>, orig_to=<>,
    > > relay=virtual, delay=3, status=bounced (unknown user:
    > > "")
    > >
    > > Jul 2 14:18:12 prupref-mailgate postfix/virtual[28097]: 7C1A3C8FBD:
    > > to=<>, relay=virtual, delay=0, status=bounced
    > > (unknown user: "")
    > >
    > This is the Bad Thing I was talking about.
    >
    > The message was accepted (queued), then later bounced. the bounce is
    > then sent to the envelope sender, which may have been forged. In this
    > case, you're sending bounces to people who never sent you mail. and
    > believe me, this is annoying. It's even worst when one gets thounsands
    > of these during a small period of time.
    >
    > This practice was acceptable in the long past. It is nowaday considered
    > as abuse, and will make your server listed in public block lists
    > (spamcops) or in private lists.
    >
    > Either reject such messages during the smtp transaction (by fixing your
    > virtual alias configuration) or setup a catchall address (which you'll
    > have to manage, but that's your problem:).
    >
    > Configure your ldap to return the virtual alias result only if the
    > "target mailbox" exists instead of using regex/pcre.
    >
    >
    >

    -- 
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  • Next message: Magnus Bäck: "Re: local_recipient_maps and backup mx"





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