Escher wrote:
>
> Protocol: SMTP, Server Response: '553 Sorry, that domain
> isn't in my list of allowed rcpthosts.', Port: 25,
Were you outside the LAN? By default, you can't send mail through your server from outside the LAN. There's no authentication built in, so anybody would be able to send mail (spam) out through your server. Having an open relay like that will get your server put on lists, and some sites will flat-out reject mail coming from any server on those lists.
If you want to send mail through your server from the internet, see
http://www.pagefault.org/code/e-smith.shtml#securemail for instructions. This will add user authentication to the SMTP server, so that you won't have to rely on physical location (the LAN) alone. It will also use SSL, so that your communications will be encrypted between your client and the mail server (normally everything is sent over the internet in plaintext).