Sometimes sending and receiving email using Outlook and Exchange Server can take a long time especially when using the SEND and RECEIVE buttons. The length of time can vary from 5 minutes to as long as 15 to 20 minutes.

It’s possible that the problem is an issue with UDP notifications to Outlook from Exchange Server. In Exchange Server 2010 UDP notifications are not issued and so Outlook, particularly Outlook 2003, is unable to register to receive notifications. And if there are any changes to a folder then Outlook will not know about those changes unless Outlook polls the server. Since the default polling interval for Outlook 2003 is about sixty seconds then at least that much time will be spent without notification of any folder changes and hence no notification of email being sent or received for that duration.

If any of the following symptoms are being experienced then there is a strong likelihood that the problem is because of long send and receives times:

• Outgoing email messages stay in the Outbox for up to one minute.
• New email messages are not arriving in the Inbox for up to one minute.
• Email messages that have been deleted from folders do not disappear from the folder for up to one minute.
• Items that are moved from one folder to another folder take up to one minute to disappear from the original folder.
• Folder updates are not occurring automatically at regular intervals

As already mentioned, this problem is more associated with Outlook 2003 because of the way it is designed to receive messages from Exchange server by using UDP for notifications. An administrator can alleviate themselves of this problem by upgrading to Outlook 2007 which uses asynchronous notification instead of UDP.

An administrator can resolve this problem with either one of two options:

1. An administrator can install the Update Rollup1 for Exchange Server 2010.
2. An administrator can use cache mode with their Outlook 2003 profile.

Here are the steps for Option 1:

Download the Update Rollup 1 for Exchange Server 2010 from article 976573, in the Microsoft Knowledge Base.

Follow the instructions to install the update. Next you will have to add the following registry data to the server by using the Client Access role. As always, you should always make a backup of the Registry before making any changes to it. The Registry is not the place to be without a backup if any errors are made when applying changes.

Here are the steps for making changes to the Registry to support the Update Rollup install:

1. Start the Registry Editor.
2. Find the following registry subkey: HKEY_LOCAL_MACHINESystemCurrentControlSetServicesMSExchangeRPCParametersSystem
3. If the Registry subkey – ParametersSystem – does not exist then create it.
4. Select and click on the registry subkey.
5. Add the following registry data:                                                                          
   Value type: REG_DWORD
   Value name: Maximum Polling Frequency
   Value data: any integer between 5000 and 120000 (decimal value)
6. Exit the Registry Editor.

Since the registry change is dynamically detected then the new settings will go into effect after the change is made and will then be applied to any new connections that clients make. An administrator can ensure that the new settings will be applied to all clients by recycling the Microsoft Exchange RPC Client Access service. This is usually done as a precaution since client connections can remain active for a long time.

And because Outlook 2003 does not poll the Exchange Server 2010 server in intervals that are less than 10 seconds, then any value less than 10000 should have the same effect.

Note that this change only enables polling to occur more frequently between Exchange Server 2010 and Outlook 2003 but does not renew UDP communication between them.

The second option for working around this problem is to use cache mode with the Outlook 2003 profile. This workaround can take the place of installing the Update Rollup 1 for Exchange Server 2010 if the install cannot be performed for some reason. Using this option will allow folder updates to occur because the cached mode synchronization process uses a different architecture.

Here are the steps for configuring your profile to use cached mode:

1. Exit Outlook 2003.
2. From the Control Panel, start Mail.
3. Click Email Accounts.
4. Click on “View or change existing email accounts”.
5. Click Next.
6. Select the Microsoft Exchange Server account and then click “Change”.
7. Enable cached mode by clicking on the “Use Cached Exchange Mode” check box.
8. Click Next.
9. Click Finish.
10. Start Outlook 2003.