CentOS - Apr 2008 - Force sendmail outbound routing for specific domain name

CentOS 4.6

Hi All:

Is it possible to force sendmail to use a specified host name for
outbound email to a selected domain name instead of the host name
that can be found by looking up the DNS entry?

The problem is that we have a client that uses the same ISP as we
do and the IP addresses assigned to both of us are very close. This
has resulted in connection problems specifically with our outbound
email to the client. I believe it is an issue with TCP/IP routing.
In the past the ISP has setup some sort of special routing that 
redirects our email to the ISP's backup mail server which then
delivers the mail to the client. Every once in a while the ISP does
something with their configuration and the routing override is lost
for several days until we can get them to recognize the problem
and then figure out what they did the last time. This happened
over the weekend and we are still waiting on the ISP to fix it up.

My thought was can we configure this in our mail server so that we
and our client do not have to suffer with this again?

TIA

Regards, Hugh

-- 
Hugh E Cruickshank, Forward Software, www.forward-software.com

On Wed, 09 Apr 2008 19:54:28 -0700
Hugh E Cruickshank <hugh at forsoft.com> wrote:
> Is it possible to force sendmail to use a specified host name for
> outbound email to a selected domain name instead of the host name
> that can be found by looking up the DNS entry?
I'm not entirely sure that I understand your problem.  If you have a unique
domain name, and your client also has a unique domain name, and your dns
records are properly configured, then sending email from domain name A to domain
name B should just work, regardless of how close your actual IP addresses are.

Having said that, you can put a domain name and IP address in /etc/hosts on the
originating computer and that computer will henceforth use the IP address
specified there.

-- 
MELVILLE THEATRE ~ Melville Sask ~ http://www.melvilletheatre.com

From: lists-centos Sent: April 9, 2008 20:29
> 
> you could use the sendmail "smarthost" setting to dump all your
> outbound mail on your isp's mail server.
We used to do that on our old SCO OSR5 box but I stopped doing that
when I switched over to the new CentOS4 system. For the life of me
I can not recall why but I must have had a reason. I will check that
out as an alternative.
> you don't explain what the problem is, e.g., inability to connect to
> their server, etc. 
The connection to the client's mail server times out.
> of course the real solution is to resolve the underlying problem
> since of course the isp's kludge will break now and then.
Too true. Eventually we will be moving the whole shebang to a co-lo
facility so that will probably avoid the problem as well (a little
overkill but it should work).

Thanks, Hugh

-- 
Hugh E Cruickshank, Forward Software, www.forward-software.com