Just to clean out the cob webs if anyone can help it would
be appreciated.

DNS server running on Netware 6.5. The issue relates to
occasional 450 host down and MX lookup errors.

DNS runs on the same server as the PO and primary GroupWise
domain. A secondary domain runs the GWIA. It's DNS resolver
(only one) points to the internal DNS server which has 4
public DNS servers configured as forwarders. Resolution
seems to be working well and I can do ping/tracert/nslookup
including mx records from any machine no problem. Every once
in a while we run into those 450 errors sending to internet
recipients that we always send to. I'm thinking it could be
an issue with the hosting network (beyond our firewall) but
to be certain we don't have internal configuration issues
I'm double checking.

What I'd like to clarify.

GWIA box, has one resolver configured (internal DNS server),
internal DNS has 4 Public DNS server forwarders, all seems
to work. Internet DNS records points the MX record to host
abc.xyz.com and that static IP is configured to reverse
lookup to abc.xyz.com (this is the first bound public IP of
the server). One of the TID I ran across indicates that
when the GWIA has receives a 450 MX lookup sending to an
internal user a route.cfg file can be used which we
configured (and I've done before so I'm sure it's correct).
The big question in this configuration is, if I create an MX
record internally, should it be matched to the public record
and point to the first bound external IP with the same host
name or should it point to the internal IP of the GWIA which
is what the TID concerning route.cfg suggests?