In the mean time, until Ipswitch fixes this, is it safe to assume that the chance 
incident of failure can be reduced by some percentage by utilizing a monstrously 
overrated processor for a given volume of mail?  --  Processor power up, chance of 
failure down, perhaps dramatically?





-----Original Message-----
From: R. Scott Perry [mailto:[EMAIL PROTECTED]
Sent: Saturday, December 06, 2003 8:33 AM
To: [EMAIL PROTECTED]
Subject: RE: [Declude.JunkMail] Declude not taking action



>We've already tracked it down about as far as it can go.  IMail's process 
>that handles the queue run is processing E-mails between the time that 
>they are saved to the hard drive (or unlocked) by the SMTPD process and 
>the time that Declude is able to re-lock the files.
>
>We are trying to think of possible workarounds.  However, since this is 
>happening at a time that Declude isn't even running, it gets very tricky.

Unfortunately, it looks like there isn't much that we can do here.  There 
are some measures we could take that would help to some extent, but not 
enough to significantly reduce the problem.

In testing here on a server at 100% CPU usage, it could take over a full 
second from the time that SMTPD32.exe unlocked the Q*.SMD file (to be 
technical, renamed the T*.SMD file to Q*.SMD) until the time that 
Declude.exe was fully loaded (versus about 50ms at 0% CPU).  Normally, the 
time to start a process isn't a problem -- almost all of that 1 second of 
time is being used by other processes.  But there is a delay of about 1 
second where there isn't any chance for Declude to lock the Q*.SMD 
file.  During this time, the file is vulnerable to being stolen by queue 
management.

On a server with 86,400 E-mails/day (to make math easier, that's 1 per 
second), a server with 0% CPU and a 30-minute queue timer would have 48 
queue runs in a day, with about a 5% chance that any given queue run would 
steal an unprocessed E-mail.  At that rate, you aren't likely to notice any 
unprocessed E-mails.  But at 100% CPU usage, there's nearly a 100% chance 
that any queue run will steal at least one unprocessed E-mail.

The good news, though, is that this should be very easy for Ipswitch to 
fix.  Specifically, the function that they use to determine if there are 
any Q*.SMD files waiting to be re-tried includes the time that the file was 
created.  They can check to see if it is less than 10 minutes old; if so, 
they can skip that file.  Since 10 minutes is the minimum amount of time 
between queue runs, E-mail that was received in the past 10 minutes does 
not need to be re-tried.  If they are worried that it would take up to 20 
minutes for an E-mail to be re-tried for the first time when the queue 
timer was set to 10 minutes, they could make the check for 1 minute (giving 
Declude ample time to start, and ensuring that first re-tries are done 
within 11 minutes).

                                                    -Scott
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