CSA (Calendar Synchronization Agent) keeps deleting mailboxes on target Exchange 2010 server (4351374)

CSA (Calendar Synchronization Agent) keeps deleting mailboxes on target Exchange 2010 server

• There is no mail synchronization, only calendar sync

• CSA keeps deleting mailboxes in a loop, the following entries can be seen in the log:
  
  1/11/2011 1:11:11 PM CExchAdmin::DeleteMailboxE2K TraceMsg 4700 Deleting mailbox '/o=OrgName/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=MailboxName'.Hard delete.

CAUSE 1

• FBSA (Free/Busy Synchronization Agent) running in parallel to CSA

• This causes mailboxes to be recreated by Exchange 2010

CAUSE 2

• Due to Exchange 2010 design, existing mailboxes need to be deleted by the agent (allowed if target mailbox is less than 100KB is size).

• The CSA will first delete the mailbox, but begin working with this mailbox only during the next sesion (this is by design, due to Exchange 2010 not allowing to create a new mailbox immediately after deleting it).

• Latency between 2 calendar synchronization cycles gives Exchange 2010 enough time to re-create deleted mailboxes

WORKAROUND 1

Stop FBSA, if it's running in parallel to CSA.

WORKAROUND 2

- Stop the calendar agent
- Rename or delete the log
- Disable all calendar sync collections
- Create one temp collection and move the affected mailboxes into this collection
- Perform a full resync for this collection
- Commit changes (very important)
- Start the CSA

WORKAROUND 3

When beginning with calendar synchronization, create a collection with a small number of mailboxes. Alternatively, create a few small collections and enable them one by one, to ensure that the interval between CSA session is short and Exchange will not have enough time to re-create the mailboxes.

Once all mailboxes have been deleted and re-created by CSA, the amount and size of the collections will not matter anymore and larger collections can be used again.

More information can be found in the QMM documentation. Avoid Incompatible Mailboxes Exchange 2010 may create unrequested empty mailboxes for mailbox-enabled users that have no mailboxes. This behavior was not present in previous Exchange versions. The resulting mailboxes are incompatible with Migration Manager and cannot be used by during Exchange migration. Instead of relying on Exchange to create mailboxes, you should delete such automatically created mailboxes and use mailbox creation settings in your migration project. Mailboxes created by Migration Manager are fully supported. However, new Exchange 2010 mailboxes should not be deleted indiscriminately, because valid target mailboxes might be deleted in the process. TheForbidDelMailbox2010 parameter has been introduced to facilitate cleanup. Previously, the "ForbidDelMailboxparameter" in the mail transmission agent's INI file was the only setting responsible for preserving or removing target mailboxes whos MailboxInfoparameter did not match the same parameter in the source mailbox. The "ForbidDelMailbox" parameter is a precaution against the deletion of mailboxes that are in actual use in the target environment. By default, it is set so that non-matched target mailboxes are not deleted.The additional "ForbidDelMailbox2010" parameter affects only Exchange 2010 target mailboxes. This parameter can have one of the following values: >Delete the new mailbox, but only if it is empty. Let the "ForbidDelMailbox" parameter define what to do with the new mailbox, but only if the mailbox is empty. Otherwise, do not delete the mailbox The "ForbidDelMailbox2010" parameter is not included in the mail transmission agent's INI file by default, and its value is assumed to be 0