"Error -2147215278 Cannot create MAPI Session object" found in the MTA log (Mail Target Agent (4258649)

"Error -2147215278 Cannot create MAPI Session object" found in the MTA log (Mail Target Agent log) and no data is processed by the MTA

Additionally, the following errors can be seen in the Mail Target Agent log.
"8/19/2010 11:44:04 AM EMWLDAP40::LDAPOperations::GetMailboxDBLDAPInfo Error 91 Object variable or With block variable not set
8/19/2010 11:44:04 AM CMBMConn::Session Error -2147215278 Cannot create MAPI Session object.
8/19/2010 11:44:04 AM CMBMConn::GetEntry Error 91 Object variable or With block variable not set
8/19/2010 11:44:04 AM CADQueue::NextItem Informational 4511 Starting to process item '/o=source/ou=First Administrative Group/cn=Recipients/cn=mailbox' (Collection "name", PST', SyncMailboxInfo: 'True', SyncSwitched: 'False', SyncAllContent: 'False', SyncFolderContent: 'False').
8/19/2010 11:44:04 AM CSession::Logon TraceMsg 4800 Logging on to the mailbox '/o=source/ou=Exchange Administrative Group /cn=Recipients/cn=ServiceMailbox (Server: '', user: 'target\serviceAccount').
8/19/2010 11:44:04 AM CSession::Logon Error -2147024809 aeMAPISession::Logon failed - invalid argument"

The Target Exchange 2010 Organization does not have a Public Folders database created and mounted.  The Mailbox synchronization agents require a Public Folders database to function.

Create a Public Folders database, ensure the target agent service account permissions are inherrited or set to this database using ADSIEdit.msc and ensure that the database is mounted.