XADM: How Moving Mailboxes Affects Single Instance Storage

ID: Q175706

The information in this article applies to:

Microsoft Exchange Server, versions 4.0, 5.0, 5.5

SUMMARY

Exchange Server maintains single-instance storage of messages even when users are moved between servers in a site.

For example, assume the following configuration:

Server 1: Users A, B, and C
Server 2: User D

When User A sends the same message to users B, C, and D, Exchange Server will make a single instance of the message on server 1 for all three users, since A, B, and C are on the same server. Even the message in the Sent Items folder of the sender (user A) is a single instance of the messages in the Inboxes of users B and C. Because User D is on a different server, Exchange Server will send a message to server 2, which will be stored on that server.

Now assume that user B is moved to server 2. Exchange Server will create a single instance of the message for B off of the copy of the message that user D has, provided that user D has not deleted the message. If user D has already deleted the message, then Exchange Server will create a single instance of the message off the copy in D's Deleted Items folder. If user D also deleted the message copy in the Deleted Items folder, then Exchange Server creates a new message and sends it to server 2.

The same process will take place if users B and C are moved to server 2. Exchange Server will maintain a single instance of the message for users B and C, based on the message in the Inbox of user D. If user D has already deleted the message, Exchange Server will attempt to use the copy in user D's Deleted Items folder. If user D has already emptied the Deleted Items folder, then Exchange Server will create a new message and send it to server 2.

Additional query words: single instance

Keywords : XADM
Version : winnt:4.0,5.0,5.5
Platform : winnt
Issue type : kbinfo