Configuring Duplicate Message Detection in Exchange Server 2007

Configuring Duplicate Message Detection in Exchange Server 2007

Sometimes users receive duplicate message. This happens when a message is sent to that user and a distribution group that includes the same user. Exchange Server 2007 store detects duplicate messages based on the following message properties:-

· Message submit time

· Internet message ID

Exchange Store uses DeliveredTo table in the JET database to keep an eye on duplicate messages. When a user sends a message, this table is checked to see if an entry exists or not. If there is no entry, then message is delivered and same entry is added in the table indicating that this message has been sent to the user. If there is an entry in the table, message is discarded.

Default value of keeping track of messages is 7 days (168 hours). We can use DeliveredTo Expiration in Hours value in the registry to change this value (Maximum 100 years). One important thing to understand is if there are more entries in the table, table will grow which will slow down the message delivery.

Exchange store deletes older items from DeliveredTo table at every hour. We can change this time by editing DeliveredTo Cleanup Interval in Seconds value in the registry.

To edit the "DeliveredTo Expiration in Hours" registry value

1. Start Registry Editor.
2. Expand the following subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\<Server_Name>\Private-<GUID>

1. Right-click Private-<GUID>, point to New, and then click DWORD Value.
2. Type DeliveredTo Expiration in Hours, and then press ENTER to name the new value.
3. Right-click DeliveredTo Expiration in Hours, and then click Modify.
4. In the Value data box, type the time, in hours, that you want to keep received message information, and then click OK.
5. Expand the following subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\<Server_Name>\Public-<GUID>

1. Right-click Public-<GUID>, point to New, and then click DWORD Value.
2. Type DeliveredTo Expiration in Hours, and then press ENTER to name the new value.
3. Right-click DeliveredTo Expiration in Hours, and then click Modify.
4. In the Value data box, type the time, in hours, to keep information on received messages before it is deleted, and then click OK.
5. Exit Registry Editor.

To edit the "DeliveredTo Cleanup Interval in Seconds" registry value.

1. Start Registry editor.
2. Expand the following subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\<Server Name>\Private-<GUID>

1. Right-click Private-<GUID>, point to New, and then click DWORD Value.
2. Type DeliveredTo Cleanup Interval in Seconds, and then press ENTER to name the new value.
3. Right-click DeliveredTo Cleanup Interval in Seconds, and then click Modify.
4. In the Value data box, type the interval, in seconds, between each execution of DeliveredTo cleanup, and then click OK.
5. Expand the following subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\<Server Name>\Public<GUID>

1. Right-click Public-<GUID>, point to New, and then click DWORD Value.
2. Type DeliveredTo Cleanup Interval in Seconds, and then press ENTER to name the new value.
3. Right-click DeliveredTo Cleanup Interval in Seconds, and then click Modify.
4. In the Value data box, type the interval, in seconds, that you want to occur between each execution of DeliveredTo cleanup, and then click OK.
5. Close Registry Editor.