Ok, this is an odd one and I'm guessing it relates to a bug as we have other NetWare 6.x servers configured the same and this problem doesn't occur.

Here is the set-up:

NetWare 6.5 SP5 (SBS 6.6)
BM 3.8 SP5

Private NIC -
Public NIC - 83.x.x.94 - DYNAMIC NAT ENABLED

With the filters unloaded I can ping 'post.demon.co.uk' without
any problems, I'm fairly sure Ping uses the Public NIC as the source address.

If I then try iptrace post.demon.co.uk source= I get
no response, I would expect Dynamic NAT to be doing it's job here?

The backup software (TapeWare 7 SP7D) has an in-built SMTP client
that e-mail's the log files to us and it's bound to the Private NIC,
so it'll need to get NATTED to send successfully...

Any suggestions how to make this work?