A connection error occurred. The destination control block index is not valid. Source locality {name}. Destination index {index name}. [{value}{value}{value}{value}] (14)

Details
Product:	Exchange
Event ID:	1026
Source:	MSExchangeMTA
Version:	6.0
Component:	Message Transfer Agent
Symbolic Name:	MTA01026
Message:	A connection error occurred. The destination control block index is not valid. Source locality {name}. Destination index {index name}. [{value}{value}{value}{value}] (14)

Explanation
The OSI stack encountered an unexpected condition during communication with the transport layer. This usually indicates that a timing window closed during a connection.

User Action
Use network Monitor to capture Network Traces, then view these traces from Network Monitor for any network issue.If the message flow is not affected, ignore the condition. If the message flow stops, contact Microsoft Product Support Services.To help Microsoft Product Support Services track down the problem, create log files. For more information, see Knowledge Base articles Q163032 and Q168906. To create Bf*.log files, select MSExchangeMTA on the Diagnostics Logging tab of the Server Properties dialog box. Then set the logging level of the APDU and X.400 Service categories to Maximum.To create APDU logs, select MSExchangeMTA on the Diagnostics Logging tab of the Server Properties dialog box. Then set the logging level of the APDU and X.400 categories to Medium or greater.