Thankyou very much for your reply.
So I need not open any port in the datacenter where exchange server is and I need to open outgoing port only in our office firewall where the BES server is residing.
So by doing this the blackberry users can send and receive emails or its one way ?
I am a bit confused here as to I just wanted to know how exactly the flow of email would be when blackbery is in place i.e. below scenario
Datacenter firewall-> Spam filter appliance ->Exchange Server ->VPN Tunnel <->Office Firewall ->BES Express Server->Outgoing port 3101
How exactly will the blackberry device interact with RIM's network via the above setup to send and receive emails ?
Thanks in advance for all ur help.