Ubuntu Servers :: Apache -> Squirrelmail Not Accessible From Internet

I set up a mail server today. Everything works except I can't access the damn squirrelmail web interface from the internet.

I followed this guide here: [URL]

I can access http://192.168.0.50/squirrelmail just fine from a computer on my local network.

*BUT*

When I access http://mywanip/squirrelmail, i get a connection timeout.

When I access http://mywanip, I get the standard Apache "IT WORKS!" Page. (Rules out port forwarding)

According to the guide, that should allow me to access squirrelmail from the internet on my server. Its as if Squirrelmail is only available on my local interface and not on my wan interface? How do I check?