"Banned Content" question - possibly a Web Bug code problem

[Quentin Campbell]

>-----Original Message-----
>From: MailScanner mailing list 
>[mailto:MAILSCANNER at JISCMAIL.AC.UK] On Behalf Of Mike
>Sent: 12 January 2005 11:53
>To: MAILSCANNER at JISCMAIL.AC.UK
>Subject: Re: "Banned Content" question - a related problem
>
>>From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
>>Behalf Of Quentin Campbell
>>
>>All the systems are now up2date as far as RH AS 3 patches are 
>concerned.
>>All the systems use the Sendmail that comes with these 
>system; the last
>>time they were updated this was Sendmail 8.12.11. I use the default
>>locking in MailScanner.
>
>I also had this problem on sendmail 8.12.10. After changing 
>the locking to posix, the problem was gone. So, although the 
>docs state that the locking problem occurs only from 8.13 on, 
>it seems that also some 8.12 versions are affected. Please set 
>the locking mechanism to "posix" and see if it solves your problem.

I will do this as a last resort. There are four reasons why I want to
investigate other things first. In particular I want to capture a
message before then after it has gone through MailSanner and got
corrupted:

1. Locking works OK on RH AS 3 systems with an up-to-date kernel.
2. The symptoms we are seeing do not appear to be repeatable so far
which makes conclusive testing difficult.
3. I have looked for other evidence of locking problems but cannot find
any. For example I can show that all messages tagged as spam by
MailScanner have been tagged once only. If there is a locking problem
you will see the same message (ie. same Sendmail QID) being tagged as
spam more than once by two or more MS processes.
4. The problem appears related to the Web Bug check. I will switch that
off first. See below for more details of this.

Having looked further at the problem it appears to be related to MIME
multipart/alternative messages having all or part of the HTML part
corrupted. The text part is not being affected. 

In all of the cases the logs show that MailScanner has "disarmed" the
HTML content. Since I only "disarm" Web Bugs it appears that there may
be a bug in the Web Bugs code that causes an intermittent problem. This
suspicion is reinforced by the observation that the problem appears to
have started when I enabled the Web Bug check late last year. I will
first of all try "Allow WebBugs = yes" and see what happens.
 
Quentin 

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