Now I have a valid domain set up thanks to tuxfamily. So, I want to have any and all email sent to my sole user lxman forwarded to my personal account. Is it necessary to set up a popbox in order to accomplish this?
Due to the heavy spam-ratio of catchall (almost 1.0 if not exactly 1.0) you can only set a catchall to a local popbox, so that we are not forwarding thousands of spams through catchalls.
Catchalls are today a very bad idea and should be avoided.
You don't need to setup a popbox for a simple mail forwarding, anyway, you can't do that ;-)