Mailing List Archive: exim: users

Forwarder destination is bogus, how to reject in the acl_smtp_rcpt?

Index | Next | Previous | View Threaded

geekinutah at gmail

Oct 2, 2009, 3:29 PM

Post #1 of 5 (788 views)
Permalink

Forwarder destination is bogus, how to reject in the acl_smtp_rcpt?

Consider this case, I am running a mail server for my domain
example.com. I have a redirect router that checks out /etc/aliases. In
that file one of my users has created a forwarder to an email address
that doesn't exist. I would like to be able to detect this at SMTP
time and reject it instead of having to generate a bounce. But a
simple

verify = recipient

doesn't seem to work. It seems to be satisfied that it can find a
match and not really care where the destination goes. Anyone know if
there is a way to do this in exim. I only want to do this at SMTP time
for local domains, if it's a remote domain I'll just take my chances,
no callout necessary.

/etc/aliases:
jon [at] example: addressthatdoesntexists [at] example

Thanks,
Mike

--
## List details at http://lists.exim.org/mailman/listinfo/exim-users
## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

awd-exim at awdcomp

Oct 2, 2009, 6:42 PM

Post #2 of 5 (735 views)
Permalink

Re: Forwarder destination is bogus, how to reject in the acl_smtp_rcpt? [In reply to]

Mike Wilson wrote:
> Consider this case, I am running a mail server for my domain
> example.com. I have a redirect router that checks out /etc/aliases. In
> that file one of my users has created a forwarder to an email address
> that doesn't exist. I would like to be able to detect this at SMTP
> time and reject it instead of having to generate a bounce. But a
> simple
>
> verify = recipient
>

All this does is check to see if the recipient domain is able to have
email delivered to do it, using DNS records.

There really is only 1 ways of resolving this, using callouts.

cya
Andrew

> doesn't seem to work. It seems to be satisfied that it can find a
> match and not really care where the destination goes. Anyone know if
> there is a way to do this in exim. I only want to do this at SMTP time
> for local domains, if it's a remote domain I'll just take my chances,
> no callout necessary.
>
> /etc/aliases:
> jon [at] example: addressthatdoesntexists [at] example
>
>
> Thanks,
> Mike
>

--
## List details at http://lists.exim.org/mailman/listinfo/exim-users
## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

exim-users at spodhuis

Oct 2, 2009, 8:19 PM

Post #3 of 5 (736 views)
Permalink

Re: Forwarder destination is bogus, how to reject in the acl_smtp_rcpt? [In reply to]

On 2009-10-02 at 16:29 -0600, Mike Wilson wrote:
> Consider this case, I am running a mail server for my domain
> example.com. I have a redirect router that checks out /etc/aliases. In
> that file one of my users has created a forwarder to an email address
> that doesn't exist. I would like to be able to detect this at SMTP
> time and reject it instead of having to generate a bounce. But a
> simple
>
> verify = recipient
>
> doesn't seem to work. It seems to be satisfied that it can find a
> match and not really care where the destination goes. Anyone know if
> there is a way to do this in exim. I only want to do this at SMTP time
> for local domains, if it's a remote domain I'll just take my chances,
> no callout necessary.
>
> /etc/aliases:
> jon [at] example: addressthatdoesntexists [at] example

If example.com is handled locally, then you have something accepting
mail at verification time for the non-existent address.

If you use:
exim -bt jon [at] example
then it should show you the redirections in a chain, with the ultimate
destination chosen for the address and the Router chosen to handle it.
That router probably is verifying inappropriately -- ie, it verifies,
but then rejects at delivery time.

If you need more debugging information:
exim -d -bt jon [at] example

Regards,
-Phil

--
## List details at http://lists.exim.org/mailman/listinfo/exim-users
## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

exim-users at spodhuis

Oct 2, 2009, 8:22 PM

Post #4 of 5 (733 views)
Permalink

Re: Forwarder destination is bogus, how to reject in the acl_smtp_rcpt? [In reply to]

On 2009-10-03 at 11:12 +0930, Andrew wrote:
> Mike Wilson wrote:
> > Consider this case, I am running a mail server for my domain
> > example.com. I have a redirect router that checks out /etc/aliases. In
> > that file one of my users has created a forwarder to an email address
> > that doesn't exist. I would like to be able to detect this at SMTP
> > time and reject it instead of having to generate a bounce. But a
> > simple
> >
> > verify = recipient
> >
>
> All this does is check to see if the recipient domain is able to have
> email delivered to do it, using DNS records.

No.

For *remote* domains, it only checks if there are DNS records. For
addresses handled locally, it verifies that the recipient can be
delivered to. I'm simplifying slightly by implying that this
distinction is by domain; it usually is.

It's worth reading chapter 3 of The Exim Specification (spec.txt with
Exim or online at www.exim.org).

-Phil

--
## List details at http://lists.exim.org/mailman/listinfo/exim-users
## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

awd-exim at awdcomp

Oct 2, 2009, 10:05 PM

Post #5 of 5 (731 views)
Permalink

Re: Forwarder destination is bogus, how to reject in the acl_smtp_rcpt? [In reply to]

Phil Pennock wrote:
> On 2009-10-03 at 11:12 +0930, Andrew wrote:
>> Mike Wilson wrote:
>>> Consider this case, I am running a mail server for my domain
>>> example.com. I have a redirect router that checks out /etc/aliases. In
>>> that file one of my users has created a forwarder to an email address
>>> that doesn't exist. I would like to be able to detect this at SMTP
>>> time and reject it instead of having to generate a bounce. But a
>>> simple
>>>
>>> verify = recipient
>>>
>> All this does is check to see if the recipient domain is able to have
>> email delivered to do it, using DNS records.
>
> No.
>
> For *remote* domains, it only checks if there are DNS records. For
> addresses handled locally, it verifies that the recipient can be
> delivered to. I'm simplifying slightly by implying that this
> distinction is by domain; it usually is.

Sorry, I am well aware of of this, I was just being a bit too
simplistic, I'll keep this in mind for future answers.

>
> It's worth reading chapter 3 of The Exim Specification (spec.txt with
> Exim or online at www.exim.org).
>
> -Phil

--
Awdcomp computing services.
Mobile: 0433 263 470
Web: www.awdcomp.net
Email: awd [at] awdcomp

--
## List details at http://lists.exim.org/mailman/listinfo/exim-users
## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

Index | Next | Previous | View Threaded

Interested in having your list archived? Contact Gossamer Threads