Transport Dumpster feature in Exchange 2007
Transport Dumpster feature was introduced on the Hub Transport role in Exchange 2007.
If you had installed a CCR, there is an instance where we need to specify a Transport Dumpster and Microsoft recommends to do so on the server which holds the Hub Transport role.
The Transport Dumpster maintains the queue of messages that were delivered to mailboxes which reside in a CCR. This helps for a lossy failover which protects data by giving option to have a clustered mailbox server (CMS) automatically come online on another node with a limited amount of data loss. Thus, in an event of a lossy failover, exchange automatically re-delivers the recent e-mail messages to user mailboxes on the failed over CCR using the transport dumpster where the e-mail messages were still stored.
The Transport Dumpster is configured by default. You can view the transport dumpster settings by running get-TransportConfig. There are two important setting when configuring the transport dumpster:
MaxDumpsterSizePerStorageGroup – The maximum size of the transport dumpster queue per storage group. This is a universal setting for all storage groups, you can’t set variable sizes for each storage group. 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 with a value of 15 MB.
MaxDumpsterTime – The amount of time an email will remain in the transport dumpster queue. This is the time a message will be retained if it is not forced out for space reasons (MaxDumpsterSizePerStorageGroup). It is recommended that this be set to 7 days.
If either of the above is set to 0, the Transport Dumpster will be disabled.
The default setting for the Transport Dumpster are:
MaxDumpsterSizePerStorageGroup: 18 MB
MaxDumpsterTime: 7 days (7.00:00:00)
If either the size limit or time limit is hit, mail will be removed from the queue by order of first in, first out.