A program that enqueues and dequeues messages may open the MTA log file, mail.log_current. For persistent programs, care should be taken that this log file is not left open during periods of inactivity. Otherwise, activities that require exclusive access to this file will be blocked. Before going idle, persistent programs should call mtaAccountingLogClose(). The log file will automatically reopened when needed.
The MTA log file, mail.log_current, is not the log written to by mtaLog().