New rules synch behavior in Exchange 2003

A solution is now available for a problem which might be encountered when moving a large number of mailboxes between Exchange servers (Knowledge Base article 899328).

When you move several mailboxes from one Exchange server to another there may be a delay in synching the rules on the new mailbox and the mailbox rules might not work for some time after the move. During the move the rules are moved in a server-independent format and are eventually converted (synched) to rule messages appropriate for the new target server. The synch takes place in a background process that fires periodically and processes a single mailbox each time the process fires, even though there might be several mailboxes that have been moved successfully and are ready to be synched. The new behavior introduced by the fix aggressively processes (synchs) the rules for all mailboxes that have completed moving since the last time the rule synching event fired.

By default, the rule synching process fires every 1 hour but can be altered by using the Rules Synch Retry Frequency registry value defined below:

HKLM\System\CurrentControlSet\MSExchangeIs\<private store guid>\ Rules Synch Retry Frequency

Value Type: DWORD

Minimum: 60

Maximum: 2592000

Default: 3600

The value is in units of seconds and the minimum value possible is 60 (1 minute) while the maximum is 2592000 (30 days). It may be tempting to set it to 1 minute to get the fastest possible synching but this may actually reduce the throughput because the average sized mailbox takes 2-3 minutes to move and only mailboxes that have completed moving will be synched. In my own tests I found that a 5 minute synching interval during a large migration worked reasonably well. If you find that the new behavior introduced by this fix is too aggressive (perhaps you notice a throughput performance problem) and would like to limit the number of mailboxes synched per rules synch event, you can use the new registry value Rules Synch Batch Limit to set a limit. It is defined as:

HKLM\System\CurrentControlSet\MSExchangeIs\<private store guid>\"Rules Sync Batch Limit"

Value Type: DWORD

Min: 1

Max: 0xFFFFFFFF

Default: All the mailboxes ready to be synched

The values are in units of “mailboxes to synch” where 1 means synch 1 mailbox per rules synch event. 0xFFFFFFFF is a special value which means “sync all” (the default behavior without this registry key).

Another related registry key you may find useful is the Rules Synch Retry Limit used to set the number of times to retry synching a mailbox if the first attempt is unsuccessful. This might be useful if there is something wrong with the mailbox which will keep the rules synch from ever completing successfully. It is defined as:

HKLM\System\CurrentControlSet\MSExchangeIs\<private store guid>\"Rules Sync Retry Limit"

Value Type: DWORD

Minimum: 0

Maximum: 250

Default: 24

If an attempt to synch a mailbox fails, an 1151 event is logged if the diagnostic level is set at medium or greater, except if the reason for failure is that the mailbox move is still in progress. Below is a sample 1151 event:

Event ID: 1151
Source: MSExchangeIS Mailbox
Description: A rule synchronization error (1144) has occurred on Mailbox Store "SG1\MB3 (SJOCA-XMB02)".
The mailbox folder is Top of Information Store\Inbox.
The distinguished name of the owning mailbox is /o=TEST/ou=TEST/cn=Recipients/cn=s140605.
There are 24 of 24 retries remaining.

An 1154 success event is logged for every successful synch if the diagnostic level is set at maximum. Below is a sample 1154 event:

Event ID: 1154
Source: MSExchangeIS Mailbox
Description: Rule synchronization has successfully completed.
The mailbox folder is Top of Information Store\Inbox on database "SG1\MB3 (SJOCA-XMB02)".
The distinguished name of the owning mailbox is /o=TEST/ou=TEST/cn=Recipients/cn=s140605.

The fix containing the solution is only available for Exchange 2003 and would therefore only be applicable for migration scenarios where the target or destination server is Exchange 2003.