Hello, We've had a stable server going for a few months now, and suddenly mail stops working. On checking, I see that the SMTP Service is 'offline'. How? Only recent modifications to the server was the installation of Isoqlog MTA Logfile Anaylzer. Could it be this logfile analyzer that is the problem?
When does postfix stops working? Have a look at your mail log. Check if the problem occurs at the same time the lofile analyzer is running.