Filename reporting issue - was: Filename enconding in auto-zip feature

Jules Field MailScanner at
Wed Sep 30 17:02:04 IST 2009

On 30/09/2009 16:39, Mark Sapiro wrote:
> On Wed, Sep 30, 2009 at 09:16:57AM +0100, Julian Field wrote:
>> I have just tried it out with a message with 3 file attached to it:
>>      Nasty&  horrible.doc .doc
>>      Nasty&horrible.doc .doc
>>      Nasty&
>> and in all cases it behaves just the way I would expect it to.
>> Other than the filenames reported, what do you actually think is going
>> wrong?
> Nothing, but the file name reporting is the problem. If the name contains
> an ampersand or perhaps other characters that are turned into %nn, in some
> cases, the 'first extension' will be dropped entirely in the report. For
> example, in the test mail I sent in the zip file attached to the message
> archived at
> <>
> the names "Motion&  Order.txt   .doc" and "Motion&  Order.doc   .doc" are
> reported as
>     MailScanner: Attempt to hide real filename extension (Motion %26 Order.doc)
> leaving the recipient and the mail admin wondering how that name triggered
> that rule.
> I don't have any problem with certain characters being escaped as %nn,
> but I do think that dropping pieces of the name, in particular in some
> cases entire 'extensions' is a problem.
It all depends on the length of the filename after the last filename 
extension has been removed. This is truncated at a fixed point. So some 
other "extensions" may be lost. I'm not sure there is any easy way, 
heuristically, of trimming the filename while leaving *all* the 
extensions, as it's unknown what is and is not an extension, and what is 
just a dot in the middle of the text of the "main" bit of the filename.


What's an extension and what isn't?


Julian Field MEng CITP CEng
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