I connect through a box running Endian Firewall (based off IPcop) which in turn is connected through a crappy ADSL router set in half-bridge mode that makes the connection and then uses DHCP to forward the WAN IP to eth0 of the Endian machine. I'm hosting an email server and a few sites off this network and dynamic DNS and everything is set up and works and I can access the lot fine from outside the LAN. Problem is the ADSL router doesn't support loopback (or something...) and I can't access it from inside the WAN using the domain name.

I'm led to believe that there isn't a way to fix this but I was thinking, the Endian box is running dnsmasq, could use the DNS part of that to have my local LAN resolve my domains to 192.168.1.10? I added an entry to /etc/hosts and added "--local /mydomain/" to the dnsmasq startup script but that didn't work at all. I can ping by domain name and it resolves to my ISPs address and pings okay but TCP packets don't get through.

Any ideas of ways I can get around this would be greatly appreciated

Hangon, if it's in bridge mode doesn't that mean that you can't access it any more? it doesn't have IP details and is just acting as a link between two identified hosts?

Just my thoughts....

The dsl router is bridging, not the Endian Firewall box..

You can use dnsmasq as you described, but you need to force users to use dnsmasq. This means forwarding any outgoing dns requests to dnsmasq.