Why not just get a pull device if that's what you want?

AKG's filter suggestion is about as good as it gets with BIS. I've read that someone was able to use the firewall to temporarily block mail delivery and not have mail queue but I don't have the details on setting that up. The advantage to the latter approach if it works is that you could enable and disable on the Blackberry itself. Editing BIS filters must be done via the carrier's BIS site.

In any case, why not get something designed to work the way you want it to work rather than rig up something on a Blackberry?