Dear all,
I am hoping that someone can help with a problem I have setting up a Solaris and sendmail based mail relay server.
The server has been built and I have been able to exchange messages between it and the mail hub. However I am having difficulty getting it to work properly now its in the DMZ.
In order to get rsolution of external mail servers I have added my ISPs two DNS addresses into the resolv.conf. This allows it to resolve externam MX addresses but it also means that sendmail is trying to send inbound mail to our external MX address. If I remove the ISP dns ip addresses from resolv.conf then sendmail will deliver to the mailhub, but external mail delivery is broken due to the inability to resolve external addresses.
So it seems I am in a catch 22.
I have the following in my mailertable which I thought would do the trick:
company.co.uk esmtp:mailhub.company.co.uk
.company.co.uk esmtp:mailhub.company.co.uk
I also have the following in my hosts table:
aa.bb.cc.dd mailhub company.co.uk
None of this seems to make any difference.
I have thought of running BIND on the mail relay. This would allow me to configure an appropriate internal MX while redirecting all other queries to the ISPs dns servers. I'm not sure about the security implications of this however. I'm told that you shouldn't use DNS in the DMZ.
Can anyone tell me what the appropriate solution for this is please and whether its OK to use BIND?
