Yesterday, I've got the information frommy Firewall admins that the activeExchange Server node(Active/Passive Cluster with Exchange 2003 SP2) is sending to much udp traffic to private IP address.I've looked inside my Exchange Server, but I can't find any information which tells me why my Exchange Server sends the udp traffic to private IP addresses.Does anybody in this Forum has a description for me, where I can find the private IP addresses inside my Exchange Server?

Hi, I would like to explain that when Exchange needs to send new email notification to client. It will use UPD protocol. For your reference: No way to configure port for UDP new mail notification packets http://support.microsoft.com/kb/264035/en-us Mike

Hi Mike,I know that the Exchange Server uses the UDP protocol to send new email notification to the clients. The client sends the IP addresses to the Exchange Server.I think that when I start a network trace I only can see that packets are delivered from the active node to the internal and private IP addresses.Where does the Exchange Server store this information?

I would like to explain that when a client starts and connects to its mailbox server, the client registers itself with the information store. The client registers its User Datagram Protocol (UDP) port and a Internet Protocol (IP) address so that the server can use this information to communicate with the client when new messages arrive. This Function is an Opnum 0x4 rpc call ecrRegistionNotification. What the client sends is it's IP address and a random UDP port number. The information store stores this data in memory Based on my current research, I do not find a method to review the stored information from Exchange server. Mike