If your company allows POP or IMAP access you can use BIS to send and receive email. There will be a 3 to 15 minute delay from the time mail hits your firms server until it hots your BB however as that is how BIS works. Plus you need a BB data plan.
Take a look at our FAQ for further info on email. Here is a link to get started:
How to add / delete email addresses - BlackBerryFAQ
I do not advise using redirector in any case. It is quite finicky, your PC must be on 24x7 and I don't think RIM supports it any longer.