it's a new setup. I'll give u some xtra nfo:
(the ip's are changed.. don't want to post them here

http machine : 192.168.0.200
runs NT4 sp6 iis5

Proxy machine : 212.0.0.1 (adsl using 10.0.0.138 for vpn)
192.168.0.199
NT4 sp6
MS DNS server (uses 192.168.0.199)
winroute 4.2
- smtp/pop server
- NAT on all communication except portmapperlist and a bunch of ip's (like primary dns)..
- proxy. (http)
- portmapper : TCP 212.0.0.1:25 -> 192.168.0.199:25
TCP/UDP 212.0.0.1:53 -> 192.168.0.199:53
TCP 212.0.0.1:80 -> 192.168.0.200:80
- packet filter:
in : permit anyip:* -> TCP 212.0.0.1:25
permit anyip:* -> TCP/UDP 212.0.0.1:53
permit anyip:* -> TCP 212.0.0.1:80
.. some other rules
block remainder

out : permit TCP 212.0.0.1:25 -> anyip:*
permit TCP/UDP 212.0.0.1:53 -> anyip:*
permit TCP 212.0.0.1:80 -> anyip:*
permit TCP 212.0.0.1:* -> anyip:80,443
.. some other rules
block remainder