Warning : Core Transport (29819) Synchronization partner is not responding (9847)

This Warning is generate when no Synchronization packets, or confirmation packets have been received from a Syncronization Partner.  One of the following is generally the cause:

1. Mail flow, or Mail routing issues between the two service account mailboxes
2. Mailbox Connectivity from Collaboration Services at one Site
3. Mail Filtering is intercepting the Messages between the sites, or moving them to a Junk Mail folder.

1. Mail Flow/Routing
• Login to the Service account mailbox at each site and send test messges between them.
• Verify Mail Queues on each sites transport server servers and SMTP relays to ensure there is not a transport failure
2. Testing Mailbox Connectivity.  In the Collaboration Services Console Right click the "Collaboration Services" node and select properties.
• On the General Properties Screen, ensure that the correct Exchange Server and Mailbox are specified.  Use the Test button to verify the service account can access the mailbox.
• Close the properties and examine the Events node for any Exchange connectivity errors or warnings
3. Ensure Messages are not being filtered
• If using an SMTP mail filter or AntiSpam technology ensure that no messages are being being blocked.  It is recommended that the Service account Mailboxes from each site be added to a whitelist to prevent any filtering.
• Loging to the Service account mailbox via OWA or Outlook to ensure that QCS related mail messages are not being moved to the Junk Mail folder automatically.  If so add the service account mailboxes to the "Safe Senders" lists for each mailbox. 
4. Verify that no errors are present in the Windows Application event logs, or Collaboration Services Events that may indicate any issues sending, receiving, or processing mail.  These may be Exchange or MAPI related errors, or Errors with the Collaboration Services Synchronization service.  You may also look at Event logs for the Exchange Mailbox or CAS servers that may show issues logging into service account mailboxes.