[CentOS] one server handled sendmail added two more servers messes things up

Michel van Deventer michel at van.deventer.cx
Fri Jan 1 20:11:28 UTC 2010


Hi,


> All three machines have the same FQDN.
> something like A.mydomain.com, B.mydomain.com, C.mydomain.com
No, they don't have the same fqdn, the fqdn includes the hostname.

> 
> The IP numbers are X.Y.Z.170, .171 and .172
> 
> All three machines have MX records. they all have the same domain name.
There's your error, the new one shouldn't have mx records for the domain
if they are not designed to accept mail for that domain.

> 
> It is a big deal to request changes from the provider so I was hoping 
> there was a way
> to just tell the two new machines that incoming email to them just send 
> on over to the the
> first machine.
> 
> Is there a way to do that - or am I going about this the wrong way?
There is a way but maybe there's a quicker (and dirtier) way. Just
reconfigure sendmail on the two new machines to *not* listen on the
public ip on the smtp port. Otherwise block port tcp/25 with iptables
(iptables -I INPUT -j REJECT -p tcp --dport 25)
But you should really get your DNS fixed.

	regards,

	Michel




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