XADM: Mailbox Store Grows When You Replicate Public Folders from Exchange Server to Exchange 2000 (810342)

CAUSE

This behavior occurs because you are replicating large amounts of public folder data. Public folder replication messages are sent as e-mail system messages in both Exchange Server and Exchange 2000. Because e-mail communication between Exchange Server and Exchange 2000 requires legacy message transfer agent (MTA) or X.400 support, these messages must be converted to the Simple Mail Transfer Protocol (SMTP) format that is used by Exchange 2000. Content conversion is completed by using a hidden folder in the mailbox store.

For additional information about how the MTA handles mail flow, click the following article number to view the article in the Microsoft Knowledge Base: If you are replicating large amounts of public folder data, the mailbox store grows to convert and store the replication e-mail messages. Latency during content conversion of a large number of e-mail messages, combined with database fragmentation, can also contribute to large mailbox store sizes.

Note Exchange 2000 can send replication messages directly from one public store to another and bypass the mailbox store.

Additionally, the mailbox store contains the replication storage table, which grows during replication. The replication storage table acts a temporary storage area while the item waits to be delivered to the public store. Online defragmentation tries to empty this table, but as the database grows, the online defragmentation maintenance window may not be large to enough to empty the table. This can prevent the database from reducing in size, and the online defragmentation process starts over in the next window, which compounds the initial problem.