MS Doesn't completely block spam with faulty attachments
mailscanner at joolee.nl
Thu Sep 1 16:31:46 IST 2011
I agree that it isn't a good idea to notify the sender of a spam or virus
message I'm not planning to do that, I know the troubles of backscatter.
What I've configured is that if a user sends a completely normal (non-virus,
non-spam) E-mail but with, for instance, a file named
"CurriculumVitae.doc.pdf" (default output for a lot of PDF printers). The
server sends out a warning to sender and the original message stripped of
it's attachment to the recipient of the message. Notifying the sender is not
strictly necessary but if this is only done for such non-virus, non-spam
message, it isn't a problem either.
The situation that bugs me is when some spam message with a file named
"CurriculumVitae.doc.pdf" is received. The message hits the filename rule
and* isn't processed any further to check if its a spam message*. Because it
isn't processed any further, the warning messages are send out to both
sender and original recipient.
As I stated before, I can disable the sender notification. What I can't do
is tell my customers (the recipients) that such wrongly named files, most
containing important documents, are silently discarded. Sending spam to my
customers that could have been recognized isn't an option either.
The simplest solution, I think, would be to *continue processing* the
message after a file name rule is hit, decide if the E-mail is HAM and in
that case, send out the notifications. If the E-mail is spam, silently
It would add a bit of load to the server but stopping spam is what it's all
about, isn't it? :P
On 1 September 2011 16:34, Julian Field <MailScanner at ecs.soton.ac.uk> wrote:
> He's probably switched on some "Notify Senders" options. Bad idea :-(
> On 01/09/2011 12:32, Martin Hepworth wrote:
>> what version of MS?
>> I never inform the sender of junk as you end up with fake messages sent
>> Martin Hepworth
>> Oxford, UK
>> On 1 September 2011 08:17, Joolee <mailscanner at joolee.nl <mailto:
>> mailscanner at joolee.nl>**> wrote:
>> Hallo Everybody,
>> I've experienced a small flood of virus E-mails. These E-mails
>> (subj.: "ACH Payment *random number* Canceled") contain
>> attachments named like: "report_082011-65.pdf.exe"
>> They obviously get blocked by the "no executables" and "No double
>> file extensions" rules. The problem is that after blocking them,
>> an automated E-mail is send to the original recipient and the
>> (faked) sender of the message, informing them of the blocked
>> Had the E-mails been processed further, they would've probably hit
>> the virusscanner (not tested) or spamassassin (gives a score of 27
>> when tested) and the E-mail would've silently been discarded as a
>> virus / spam / phishing.
>> Is it possible to let the MailScanner continue it's processing
>> when hitting the file name rules and / or running the filename
>> rule at a later time?
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>> Julian Field MEng CITP CEng
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>> PGP footprint: EE81 D763 3DB0 0BFD E1DC 7222 11F6 5947 1415 B654
>> Follow me at twitter.com/JulesFM
>> 'It's okay to live without all the answers' - Charlie Eppes, 2011
>> 'All programs have a desire to be useful' - Tron, 1982
> This message has been scanned for viruses and
> dangerous content by MailScanner, and is
> believed to be clean.
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