Mailscanner generated duplicate message

[Glenn Steen]

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?

Cheers
-- 
-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se