New mail notification messages are sent by means of UDP
packets from the server to the client. The ports used for this notification are
set by the client when the client logs on to the information store.
As part of the log on process to the information store, the client tells the
server the IP address and port where it expects to receive new mail
notification messages. This will be a UDP port in the 1024-65535
range.
When the server receives a mail message for a mailbox that a
client is logged on to, it opens a UDP port dynamically, and sends a packet to
the IP address and port registered by the client logged on to that
mailbox.
Because the client picks a port at startup and the server
does not always use the same port when sending the notification, there is no
way to predict either the source or destination ports that this traffic will
use.
For clients to reliably receive new mail notification packets,
you must enable traffic as follows:
Setting Value
------------------------------------------
Protocol ID UDP
Direction Exchange Server --> Client
Local Port >1024
Remote Port >1024
The "Client" in this table can be specifying either
specific client IP addresses or the networks where the clients reside. Your
filtering device documentation will have information on how to actually
implement the filter.
Note Microsoft Outlook 2003 includes a registry key that allows the setting of a static UDP port for new mail notification packets. This registry key is available only in Outlook 2003 or later. You can modify the following registry key to specify a UDP port number.
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\RPC
Registry Entry: FixedUDPPort
Value: DWORD
The decimal value of the port number must be between 1024 and 65535.