What makes you think there isn't? All web mail systems, including VM's, allow checking of several e-mail addresses at once and some offer combined in-boxes (VM's certainly does) so you can see all your mail in one place. The VM help files on this are simple to follow. Add each VM address, one at a time, and when you log in you'll collect all the mail for each address instantly (well as near instantly as VM can manage). The system works as web mail for the main address and like an IMAP client for the additional addresses you add.