A mailbox is a part of mailbox or calendar synchronization collection, but it is not getting synchronized. The EMWCSA.log or EMWMSA.log contain an error similar to the following:
"08/11/2006 07:00:30 CMBMConn::GetMatchKey Warning 4810 No matching was found for '/o=ORG/ou=EU/cn=Recipients/cn=user'. Please make sure that the user is migrated, the matching rules are correct, and the script components are functioning."
The legacy agent is unable to locate matching mailbox on the target side, so the mailbox is ignored.
Please check the following
1. The object referenced in the log has been successfully synchronized by Directory Synchronization Agent
2. Corresponding target object exists and the service attribute (Extension attribute 15 by default) has a value that is equal to the objectguid of the source user.
3. Start Quest Migration Manager, expand the source orgnization down to the server where the agent is installed, right-click it and select properties. Browse to Associated Domain Controller page and verify that the correct domain controller and credentials are specified.
4. Open source object properties with Acitve Directory Users and Computers. On the Exchange addresses tab verify that there is an X500 address containing the LegacyExchaneDN attribute of the corresponding target object.
5. Ensure the target mailbox is not hidden from the GAL.