[CentOS] Force sendmail outbound routing for specific domain name

Thu Apr 10 03:32:00 UTC 2008
Clint Dilks <clintd at scms.waikato.ac.nz>

Hugh E Cruickshank wrote:
> From: Frank Cox Sent: April 9, 2008 20:01
>> 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.
> I agree whole heartedly that it "should just work" but time and time
> again we have see where it does not work.
>> 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.
> That would work if I was looking to use a specific IP address but
> would like to use a specific host name. For example I would like
> all mail outbound to example.com to bypass the DNS/MX entry of
> mail.example.com and use instead backupmx.isp.com not just the IP
> Address of backupmx.isp.com.
> Thanks muchly for your suggestion.
> Regards, Hugh
Hi, It has been some time since I have had to do anything with Sendmail 
like this, but I believe mailertable is what you need. See 

Hope this helps :)