Mailscanner generated duplicate message

[Julian Field]

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Glenn Steen wrote:
> On 08/02/2008, Glenn Steen <glenn.steen at gmail.com> wrote:
>   
>> On 08/02/2008, Glenn Steen <glenn.steen at gmail.com> wrote:
>>     
>>> On 07/02/2008, Cedric Devillers <cde at alunys.com> wrote:
>>>       
>>>> Hello,
>>>>
>>>> I'm trying to revive this thread from the last month because we are
>>>> observing the exact same behavior on one of our servers.
>>>>         
>>> Thanks for doing that, and for providing some more info.
>>>
>>>       
>>>> So to remember the facts :
>>>>
>>>> - We are using mailscanner with postfix, and duplicated messages are
>>>> generated by mailscanner.
>>>>
>>>> - This system is the only one where we are observing this behavior. It
>>>> have a little particularity : it mainly act as a mail relay, but
>>>> sometimes many mails are generated by the server itself (a script) and
>>>> injected in postfix queues via sendmail command. We can always reproduce
>>>> some duplicated messages with this script.
>>>>
>>>> - MailScanner is configured (by ruleset) to bypass scanning for thoses
>>>> messages, but they are still entering the mailscanner logic (postix ->
>>>> hold queue -> mailscanner (no scan) -> active queue).
>>>>         
>>> What does the ruleset look like? I'm sure it doesn't matter, but ...
>>> just out of curiosity:-)...
>>>
>>>       
>>>> - Mailwatch is running on this server, and for each duplicates we see
>>>> entries with null size body (2, 3, 4, sometimes 5) then at last a final
>>>> entry with the full body. Note that the recipient see the full body on
>>>> every duplicate.
>>>>
>>>> It looks like a locking problem, because all duplicates are with the
>>>> same postfix queue ID and different entropy part (ID.xxxx, ID.yyyy,
>>>> ID.zzzz, etc). Can it be possible that a mailscanner child "fail" to
>>>> lock some queue file when message is marked not to be scanned by
>>>> mailscanner ?
>>>>         
>>> Yes, this seems plausible... Could you provide some log examples? Just
>>> to see that it really is separate children reading the same queue
>>> file...
>>>
>>>
>>>       
>>>> I will not be very helpfull to debug perl code, but i can provide any
>>>> needed logs to help finding the origin of the problem.
>>>>         
>>> I'll see what I can do, but... I think this isn't "my" code snippets,
>>> but a thing that might have been present for a while... And I have a
>>> serious lack of time to spend on this ATM (worse than last time,
>>> before Xmas)... So no promises:-).
>>>
>>>       
>>>> This is really a serious problem in this particular installation. But i
>>>> must say that we have dozens of other servers that are running
>>>> mailscanner/postfix, and we are very happy about thems :)
>>>>         
>>> Does it help if you DO scan with MS, but skip things at the next
>>> level, for example:
>>> Scan Messages = yes
>>> Use SpamAssassin = no
>>> Dangerous Content Scanning = no
>>> ... and possibly a few more (do them with a ruleset, of course:-)?
>>>
>>>       
>> BTW, do you have any milters enabled in Postfix? What version of Postfix?
>>
>> Cheers
>>     
>
> I think we need Jules on this one, not only feeble lil' me:-).
> AFAICS, the locking/unlocking is handled _exactly_ the same regardless
> of the scanmail setting... But then, this is a rather complex bit of
> code, where the "execution path" isn't always as straightforward as it
> seems... Jules, could you spare a moment or two? Just to look at what
> could possibly be wrong with the message->scanmail = 0 scenario?
>
>   
Can you *briefly* explain what the problem is, what the symptoms are and 
where you think the problem might lie? This is a very long thread.... :-)

Jules

- -- 
Julian Field MEng CITP CEng
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