What's the difference between a POP account and an alias (or forward)?
By default, your account is setup to receive all emails sent to firstname.lastname@example.org in the main pop email box of your account, which by default is email@example.com
You do not have to edit anything to accomplish this. The difference between a pop account and an email alias (or email forwarding), is that a pop account has its own login and password. An alias simply forwards to somewhere else.
As described above, any alias not specifically told to forward elsewhere is automatically forwarded to the main pop account of firstname.lastname@example.org