Topic Last Modified: 2009-03-05

This topic describes how to use the Exchange Shell or the Exchange Management Console to resolve an issue in which you receive duplicate e-mail messages or delivery status notifications (DSN) after a cluster continuous replication (CCR) cluster fails over unexpectedly in a Microsoft Exchange Server 2007 environment.

This issue may occur if the MaxDumpsterSizePerStorageGroup parameter for the Transport Dumpster feature on the Hub Transport server is set to 2 gigabytes (GB) or more. After the CCR cluster fails over, the messages that are retained by the Transport Dumpster are dropped immediately into the mail queue. This large amount of mail can include messages that are several hours old. By default, the DelayNotificationTimeOut value on the Hub Transport server is four hours. For each message that is dropped into the mail queue and that is more than four hours old, the categorizer generates a DSN when the messages are resubmitted. When the messages move to the mailbox store, the messages may also be duplicated.

To resolve this issue, reduce the size of the MaxDumpsterSizePerStorageGroup parameter on the Hub Transport server. The recommended size is 1.5 times the maximum message size that can be sent. For example, if the maximum size for messages is 10 megabytes (MB), you should configure the MaxDumpsterSizePerStorageGroup parameter to have a value of 15 MB. To set the MaxDumpsterSizePerStorageGroup parameter on the Hub Transport server, use the Exchange Management Shell or the Exchange Management Console.

To use the Exchange Management Shell to configure the MaxDumpsterSizePerStorageGroup parameter on the Hub Transport server

  1. Open the Exchange Management Shell.

  2. Type the following command, where <size> is the appropriate value, and then press ENTER:

    Set-TransportConfig -MaxDumpsterSizePerStorageGroup <size>

To use the Exchange Management Console to configure the MaxDumpsterSizePerStorageGroup parameter on the Hub Transport server

  1. Open the Exchange Management Console from a management workstation that is running Exchange Server 2007 Service Pack 1 (SP1).

  2. Expand Organization Configuration, and then click Hub Transport.

  3. On the Global Settings tab, double-click Transport Settings.

  4. In the Transport Dumpster area, type the appropriate value in the Maximum size per storage group (MB) box, and then click OK.