In some cases the mail agent creates a PST file, tries to log in, then logs off and deletes the PST file and the following entry can be seen in the log:
MailKernel::Work TraceMsg 2061 Synchronization has been completed. (RetCode: -2147221502).
What does this entry mean?
This entry is being logged when the agent finishes the work unexpectedly, eg. when the service gets stopped, etc.
Analyze the log file, usually the previous entries will contain an explanation.
This entry is eg. being logged after a following error in the log:
CSession::Logon Error -2147221231 The information store could not be opened. - MAPI_E_LOGON_FAILED (MAPI 1.0) Low level error: 0x0 File: 'aeWrapHelpers.h' Line: '279'
12/27/2011 5:23:55 AM MailKernel::Connect Informational 2079 Synchronization status: Object '/o=ABC/ou=DEF/cn=Recipients/cn=user' synchronization was not started due to connection errors.
In this case the agent cannot open the store in the mailbox. This is being considered as a critical error and triggers a Terminate command, and this results with the mentioned above tracing entry in the log.
Try to use MFCMAPI on the server where the agent is installed and to try to open the affected mailbox and all the folders inside.