|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 Ap*.log files, in the Diagnostics Logging tab of the Server Properties dialog box, select MSExchangeMTA and set the logging level of the Interoperability and Interface categories to Maximum. To create Bf*.log files, set the logging level of the APDU and X.400 Service categories to Maximum.Save all MTA log files (mtadata\*.log), Event Viewer output, and database files. Contact Microsoft Product Support Services.You can enable text event log files (Ev*.log) by modifying the Registry. Contact Microsoft Product Support Services for assistance.