[Techtalk] sendmail config questions

Dennis Wheeler wheelers at eskimo.com
Sat Aug 9 01:50:34 EST 2003

On Sat, 9 Aug 2003, Rudy L. Zijlstra wrote:

> Dennis Wheeler wrote:
> >
> >I've got a remote server running RH 7.1 and sendmail 8.9 (I think)
> >
> Hmmm, upgrade to the latest version (8.12.9 last i looked), it has
> several security fixes. As far as i know 7.1 is *old* and i have no clue
> whether RH is still bringing out patches for it. You may have to install
> from source. I have to admit i do not track RH (do not use them).

We'll eventually upgrade, but that'll require a plane trip. I'd like to
just get them up and running again first.

> >I suspect it might be an open relay, so I need to 1) turn that off if
> >it is and 2) verfiy that's it's not afterwards.
> >
> This is default off on the later releases. You have to explicitly enable
> it to get an open relay with those

That's what I thought, but I wasn't sure how to verify it to be one way or

> >It is accepting messages now, but they are just being queued and not
> >delivered. They are running an exchange server that their clients are
> >accessing via pop (again, I'm not sure here), but I don't see where the
> >mail is being forwarded from the linux server to the nt server.
> >
> Does it have a direct connection to the internet, or should it forward
> mail to the exchange server?

It's behind a firewall, but it is accepting connections to port 25

The logs show incoming messages, but they are being queued. It should
forward them to the exchange server.

I did try just now telneting to port 25 on the exchange server and sending
mail to a local mailbox. The exchange server seems to be queueing them as
well -- I'll be asking the NT admin about that in the morning.

> >And their internal domain name is different from their external domain
> >name. I tried sending a test message and eventually got an warning
> >response "Could not send for 4 hours", with a name sever timeout error, so
> >I'm suspecting this domain name difference may be the problem. They're
> >
> Not likely. Most probably a nameserver misconfiguration on the redhat
> install. When sendmail has no dependable DNS access, it cannot deliver mail.

resolv.conf points to the internal dns (running on nt) as primary, and the
isp's dns as secondary

The problem I see is that the isp's dns only knows abcd.ext.st.us (not
real btw) and the internal dns only knows abcd.edu

> >running an internal DNS on the same nt server as their exchange server, so
> >I don't quite know how to query and/or modify it remotely
> >
> >I'm currently reading RedHat's sendmail howto and lots of stuff on
> >sendmail.org. But there's so much, I'm getting lost.
> >
> >I'd appreciate some suggestions.
> >
> >Thanks,
> >Dennis
> >
> >
> You likely need to tell sendmail to accept mail from both domain names.
> I cannot tell more without knowing more about the setup.

Is that in the sendmail config? or the MX records in the DNS? or both?

> Cheers,
> Rudy

Thanks so much for your help so far.


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