[Mimedefang] Re: SMTP mailertable question

[Cormack, Ken]

A follow-up to the MX records for smarthost question:

After consulting the 3rd edition of the O'Reilly Sendmail book (the "bat"
book), and the sendmail/cf/README file in the source tree, and reading all
that I can find about the sendmail smarthost, I can find no description that
indicates MX lookups are done for any name defined as the smarthost.
There's plenty of discussion of MX lookups and destination list building
when reading about Fallback MX hosts and such, but no discussion of that
nature, with the smarthost setting.  :'(

Looks like my cron script will do, for the time being.

Ken

-----Original Message-----
From: mimedefang-bounces at lists.roaringpenguin.com
[mailto:mimedefang-bounces at lists.roaringpenguin.com]On Behalf Of
Cormack, Ken
Sent: Tuesday, December 30, 2003 1:26 PM
To: 'mimedefang at lists.roaringpenguin.com'
Subject: RE: [Mimedefang] Re: SMTP mailertable question


That would be one way to go about it.  But perhaps here's a possibility.
This may probably be best sent to the BIND9 list, but perhaps it's worthy of
this list too (given that this is where the discussion started.)

In my internal DNS, I have an existing subdomain referencing the internal
addresses of my DMZ machines.  Without having to create subdomains or set up
additional caching servers, would it work to just define my dummy smarthost
name with a bogus address in my DMZ-referencing zone, and the also define
two host-specific MX records for the dummy smarthost entry?

DNS allows for the creation of host-specific MX records.  If I added two
such records, and the dummy smarthost record, the process might work.  I
just dont know... When sendmail tries to resolve the "SMARTHOST", does it
ONLY make A-record lookups from DNS?  Or does it first try an MX lookup on
the host defined as the smarthost?  In the first case, defining
host-specific MX records would not work.  In the latter, it just might be
the most elegent solution.

Does anyone have any thoughts?

-----Original Message-----
From: mimedefang-bounces at lists.roaringpenguin.com
[mailto:mimedefang-bounces at lists.roaringpenguin.com]On Behalf Of David
F. Skoll
Sent: Tuesday, December 30, 2003 12:29 PM
To: 'mimedefang at lists.roaringpenguin.com'
Subject: RE: [Mimedefang] Re: SMTP mailertable question


On Tue, 30 Dec 2003, Cormack, Ken wrote:

> Doing as you suggest with MX records, though it could be cool, requires
the
> creation of a seperate DNS domain.  And at the moment, our DNS is in a
> transistion period as Active Directory is melded with BIND 9.

But you can run a caching nameserver on your Sendmail machine and add
your own fake zone just for the mailertable purpose.  It's easy and doesn't
impact the rest of your network (no other machines need know about it.)

--
David.
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