In some email I received from Alicia da Conceicao, sie wrote:
[...]
> Unfortunately this does not appear to be true, since RDR is only
> able to forward a port from an arbitrary IP number to/from *ONLY*
> one external interface.
[...]
> For example, if I am on remote client on the Internet with an
> arbitrary IP number, and I run:
> 
> 	telnet 231.231.231.231 25	(external interface ext1)
> & 	telnet 123.123.123.123 25	(external interface ext0)
> 
> If I am running sendmail locally on the KAME+NetBSD server, then
> that remote client can type in SMTP commands with *EITHER* telnet
> command, and sendmail will process and repsond to those commands.
> 
> If I am using RDR to forward port 25 to an internal mail server
> with sendmail instead, and I use the following IPNAT rulesets:
> 
> rdr ext1 231.231.231.231/32 port 25 -> 192.168.0.133 port 25 tcp
> rdr ext0 123.123.123.123/32 port 25 -> 192.168.0.133 port 25 tcp
> 
> then only the *FIRST* telnet command will work and be forwarded, and
> will not work for the second.

I just don't have enough resources to even attempt to try this myself.

All I can say is you will have to use the tools available to try and
work out what is happening (and not happening) to the packets.

Darren

p.s. your "Cc" list was very unfriendly.