A forwarder (with the apprioriate reply-to configured in BIS) would let you do this. For example, I have my main personal email on my own domain
. In my web host's mail configuration, I have the option to forward email for a certain address. I set it to
, and then in BIS I set my reply-to address to be
, that way mail sent from my BB using that account appears to some directly from my personal account. This is instantaneous, no waiting for the 10-15 minute poll. It's even much faster than Redirector, which I use for work email.