We have a number of customers that use BIS and forward their corp email to their BB address. This works pretty well for hundreds of users. I have one set of users however that is having trouble. Their forwarded mail sits on their mail server queued for vzw.blackberry.net for hours. Some mail goes through in real time but allot is just sitting there and getting a "Remote System not longer responding". Eventually it gets delivered but why the delay? Anyone got any ideas?

You should open ticket with RIM.

Is the delayed mail sitting on the RIM server or on your company server? If it's the latter (company server): some companies have multiple servers (and in some cases, multiple locations), and individual user email addresses and mailboxes reside on more than one server. Mght be worth checking to see if the delayed mail is all coming from the same server.