ZCS is setup behind a firewall with all the necessary ports forwarded. Bind is running on the ZCS to tell it that it's internal ip address resolves to it's external name. That stuff all works fine.

I have a second host that I want to deliver mail to on the internal network. It is not on the same dns zone that is configured on the local bind and I have a forward zone set up on the ZCS to get the data about my other internal zone.

ZCS is able to resolve it using it's resolv.conf hitting the local Bind and getting the forwarded zones from the internal dns servers. It can ping the host and everything looks fine.

When I try to send a mail using my SMTP client to ZCS the mails get deferred with the error "No Route to Host" But that isn't true from the Linux under ZCS's point of view. So I'm not sure what to do next.

  • ZCS Hostname: mail.mycompany.com
  • Internal DNS Zone: something.com
  • Host I'm trying to send mail to:help.something.com
  • Email: support@help.something.com

ZCS Bind configs:
zone "mail.mycompany.com" {
        type master;
        file "/etc/bind/db.mail.mycompany.com";

zone "mycompany.com" {
        type master;
        file "/etc/bind/db.mycompany.com";

zone "something.com" {
        type forward;
        forwarders {; };
Reason: connect to help.something.com[]:25: no route to host
Any suggestions would be appreciated.