Problems with idle pop3 connections locking mailboxes

Michael Sims michaels at
Mon Jul 12 19:54:36 EDT 2004

Michael Loftis wrote:
> --On Monday, July 12, 2004 17:16 -0500 Michael Sims
> <michaels at> wrote:
>> As promised, I'm following up to the list on the status of this
>> problem, in case anyone has an issue like this in the future.  It
>> does appear to have been caused by our intrusion detection device.
>> Our network manager configured this device to avoid scanning POP3
>> connections and for the past two weeks I have not seen any more pop3
>> daemons stuck in the middle of a write().  I may be jinxing myself
>> by saying that the problem is resolved but it certainly appears to
>> be so.
> write() to disk or network?  if network then sounds like a nasty
> deadlock in the NIDS.  i never did like NIDS that required inserting
> themselves into the traffic stream.

write() to network.  The problem always occurred with clients downloading
messages larger than about 1.5 MB over POP3.  The appliance we have does
operate in so-called "transparent" mode.  Apparently it isn't "transparent"
enough. :)

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