direct mail to other mailbox

I believe the answer must be in the 300pps. pdf. manual, but I haven't found it.

I lost my public (posted on my website) email account last week.  I am thinking of
creating an email address for that site and run it through a server with my other
emails on it.

I would like the new email for the website when it comes into the account to be
directed to another mailbox within that account.

So when an email comes in addressed to that particular name it would go to a
separate mailbox within that account.

How do you do this?

If this can be done, would it be specific to everything before and after the "@"?
Or would it apply only to after the "@"?

Thank you,
MU