New GW8 domain on a OES2 server.
Existing GW6.5/Netware CS setup in a different tree.

Can send internet email from GW8 to external pop3 accounts and it is delivered very quickly.
If I send externally to the GW6.5 setup then its slower but does get there eventually.

In both cases a reply just dissappears, as does an orginal message to the GW8

This is probably a DNS error or a firewall mistake of some kind, but any pointers?

GW8 is on a international domain and getting DNS entries changed is a slow process.