For how to add each type of mailbox go to:
Adding a Subscriber or Guest mailbox
Adding a Fax On Demand mailbox
When you add a mailbox, for each type of mailbox use a mailbox number that begins with the same digit. This helps you identify the mailbox type. For example, all Information mailboxes can begin with 4 and all Guest mailboxes can begin with 5.
When you create a name for a mailbox, do not use a name that begins with 1, for example "1Smith" for a Subscriber mailbox, or "1Info" for an Information mailbox.
To change a mailbox, click the Change link for the mailbox and go to:
Changing a Subscriber or Guest mailbox
Changing an Information mailbox
Changing a Fax On Demand Mailbox
Changing a Fax Overflow mailbox