I just had a look through the messages and can not see where I mentioned configured the server but the way I set up the server is as follows:
1. Set up my DNS with my domain provider (123-reg)
2. Ran the set up wizard for the server followed all steps, with no issues.
3. Set up all the port forwarding.
4. Set up user in the server.
5. Switched on Mail in the server (did not make any changes).
6. Set up the user on Mail on my MacBook Air
I first tried sending an email to the new set up address = no problems, then tried sending a message which is where I am now.
When I spoke to Apple the guy had me send a message from the address to itself and this worked no problem (maria@hiscock.me to maria@hiscock.me) seem to be a problem when going out to the real world.