This sounds like a UDP issue. This issue occurs because Outlook uses the user
datagram protocol (UDP) to receive new e-mail message notifications, to
update folder views, and to perform searches.
When making an initial connection to an Exchange server, Outlook registers
itself for new message notifications. Whenever a new message is received in
an Outlook user's mailbox, Exchange sends a notification to Outlook using
UDP. This notification is essentially a small flag to the client that a new
message is present and needs to be displayed. When Outlook receives the UDP
notification, it retrieves the message from the Exchange server and displays
it in the appropriate folder (e.g., the Inbox).
New message notifications are intended for Outlook clients that are running
in either online mode or Cached Exchange Mode, and they won't work for
Outlook clients using RPC over HTTPS. In fact, when using RPC over HTTPS,
Outlook does not register for notifications (because it won't be able to
receive them). Instead, Outlook clients using RPC over HTTPS use a polling
mechanism to check for new messages. While polling is initiated by Outlook,
the polling frequency is dictated by the Exchange server. Polling is not new
to Outlook 2003; Outlook 2002 automatically reverts to polling if the UDP
notification fails. However, new in Exchange 2003 is your ability to
configure a polling interval for RPC over HTTPS clients.
With Outlook 2000, if you're using NAT then Outlook never receives the UDP
packet that Microsoft Exchange sends. To resolve the problem, ensure the
Outlook clients are running SR1a. If SP3 has already been applied then you'll
have to manually edit the registry.
To add the registry values to the computer that is running Outlook 2000,
follow these steps: 1. Click Start, and then click Run.
2. In the Open box, type Regedt32.exe, and then click OK.
3. Locate the following key in the registry:
HKEY_CURRENT_USER\Software\Microsoft\Office\9.0\Outlook\
4. On the Edit menu, click Add Key, and then add the following registry key:
Key Name: RPC
Class: None
5. Click OK.
6. Locate the following key in the registry:
HKEY_CURRENT_USER\Software\Microsoft\Office\9.0\Outlook\RPC\
7. On the Edit menu, click Add Value, and then add the following registry
value:
Value Name: ForcePolling
Data Type: REG_DWORD
Value: 1
8. Locate the following key in the registry:
HKEY_CURRENT_USER\Software\Policies\Microsoft\
9. On the Edit menu, click Add Key, and then add the following registry key:
Key Name: Office
Class: None
10. Locate the following key in the registry:
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\
11. On the Edit menu, click Add Key, and then add the following registry key:
Key Name: 9.0
Class: None
12. Locate the following key in the registry:
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\9.0\
13. On the Edit menu, click Add Key, and then add the following registry key:
Key Name: Outlook
Class: None
14. Locate the following key in the registry:
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\9.0\Outlook\
15. On the Edit menu, click Add Key, and then add the following registry key:
Key Name: RPC
Class: None
16. Locate the following key in the registry:
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\9.0\Outlook\RPC\
17. On the Edit menu, click Add Value, and then add the following registry
value:
Value Name: ForcePolling
Data Type: REG_DWORD
Value: 1
18. Quit Registry Editor
19. Restart the computer.
