if I post under my alias & an PM'D will it show up in my username email?

If you post under an alias what about your pm?I am sorry I am not following what you are asking

...you have to be careful if you reply to a PM sent to your alias.  If you reply, you have to change the "From" box from your real handle to your alias in order to keep from revealing your real handle.

If the last time you posted on a board using your alias your future posts will come up with your alias as well unless you switch over.