Can u add multiple blackberry units to one exchange mailbox??
So both units can send and receive mail for the one mailbox.

I am running my all my berries on the BES.

Unfortunately, no. There is a one-to-one mapping between Blackberries and mailboxes on the BES side.

The closest you would be able to come to this is to setup another mailbox on your Exchnage server and have all of the messages from the first mailbox forwarded to it as well (you can do this in the Exchange User Manager).

This would handle incoming messages, but wouldn't necessarily work for outgoing addresses (since outgoing messages would be sent with the from address of the secondary mailbox).

If you could explain what you're specifically trying to accomplish (ie, why you want to do this), perhaps we could offer some better suggestions...

is there a way on the bes to have the outgoing address set to whatever you like? there is a way on the BWC to do this.

Unfortunately, no. Since the mail is delivered via the Exchange mail system, it will go out with whatever address the Exchange mailbox is set to.

There are some Blackberry tools that may allow you to modify the "Reply-To" address, but they won't change the actual "From" address.

Another possible solution to the above if it were crucial that mail come from the single address would be to use BWC and poll the Exchange mailbox through POP3/IMAP4.... However, this is a much more messy solution.