Beginner Question

Andreas Kasenides Andreas.Kasenides at
Wed Nov 21 12:32:40 GMT 2007

UxBoD wrote:
> Andreas,
> 1) As part of the installation for Postfix and MailScanner the file is changed so that a header check is performed on every email that is processed.  As "Received" appears in all messages, RFC compliance, then the message is put into a hold queue.  MailScanner monitors this directory and when it sees messages it will process them, and on successfully processing, will the deliver them into the outbound queue for Postfix to deliver.  If MailScanner was to die half way through processing a message it would still be safe, as it does not remove the message from the hold queue until such time successful processing has taken place.
Let me elaborate a little further on this issue:
Excuse me if I insist on this and correct me if necessary. The HOLD 
queue is NOT an inactive queue
as Glenn suggests but rather a different kind of queue (from the 
incoming queue for example)
in that messages are put there by Postfix and forgotten rather than 
being continuesly monitored.
The issue though is how does MS make sure that during its routine scanning
of the HOLD queue it does not pick up one of the messages that are just 
being written
(and not finished yet) by Postfix.
In other words is it your understanding that Postfix properly "locks" 
the files and that MS properly
detects the locks to avoid any mishaps.
I expect that the above is standard these days and therefore the only 
issue that remains is for MS
to properly understand the Postfix queue file format. Correct?

thanks a zillion for all clarifications

> 2) Yes the queue file structure is their "own internal thing", but we are talking about OSS here so anybody is free to view the code and make the necessary changes to MailScanner.  Obviously when upgrading Postfix on a server you have to ensure that the revision being installed is compatible with MailScanner, so when they do/if change the structure wait until a suitable MailScanner revision has been released.
> This is purely my understanding, and I am sure somebody will correct my mistakes ;)
> Regards,
> --[ UxBoD ]--
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> ----- Original Message -----
> From: "Andreas Kasenides" <Andreas.Kasenides at>
> To: "MailScanner discussion" <mailscanner at>
> Sent: Wednesday, November 21, 2007 9:16:04 AM (GMT) Europe/London
> Subject: Re: Beginner Question
> I am a relatively newcomer to the MailScanner land but I have been running mail servers 
> (sendmail for too many years to admit and postfix for the last 3 years) and I have come 
> across this Postfix-with-MS incompatibility issue. Apparently the Postfix developers 
> are seriously anti-MS because MS DOES not use their own way of message passing 
> between the SMTP processes and the MS processes (apparently they recommend LMTP). 
> I have read a lot of this on the Postfix lists and while there is a serious issue of how 
> a message is moved from the SMTP service to the virus/spam-detecting service I have come to the 
> conclusion that there are only a couple of issues that need to be clarified from the MS point of view 
> (the rest seems politics to me which I cannot comment since I do not know the players involved): 
> 1. How does MS make sure that when dealing with the incoming Postfix queue it does not ake a mess 
> of it? In other words how does MS know that a message in the queue is free and ready to be processed 
> and that Postfix is not working on it? 
> 2. Apparently the Postfix guys believe that the queue file structure is there own internal "thing" 
> which they do not or would not make public and if a new upgraded structure is created MS will fail miserably 
> upon Postfix upgrade. Remember that MS depends on this structure to properly make changes in the 
> files. 
> I was very suddened by the discussion in the Postfix lists. In my view this sort of thing should 
> happen in the commercial software world, not on open source projects. 
> I would appreciate an answer (even if it is obvious) from somebody that knows enough of the internals 
> of MS. 
> thanks! 
> Andreas Kasenides 
> Joseph L. Casale wrote: 
> Hi, 
> I was looking for a complete tutorial to setup a mail filter for our existing server and came upon the following article ( ) but reading the comments below it, it stated the implementation of Mailscanner with postfix in this manner was unsupported? 
> Can you guys confirm or deny this, and if so possibly recommend a similar tutorial? 
> Thanks for any input! 
> jlc 

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