Mailscanner corrupting pdf files

Martin Sapsed m.sapsed at BANGOR.AC.UK
Wed Jul 23 19:16:32 IST 2003

Plant, Dean wrote:
> I am having a problem with pdf files corrupting when passing through the
> Mailscanner. If a mail with a pdf attachment is sent from one of our
> clients, MS exchange encodes the message as either base64 or
> quoted-printable format. All messages that are encoded as base64 pass
> through the MailScanner correctly. Quoted-printable format mails have the
> attachment corrupted. Turning off virus checks on Mailscanner allows the
> quoted-printable mails to pass through without corruption, so I assume it
> has something to do with:
> 1. Perl Mime::tools - Is this decoding / encoding the attachment correctly?
> 2. MS Exchange - Why encode some pdf's as base64 and some as
> quoted-printable
> 3. Different versions/creators of pdf files.
> Has anyone else suffered from this problem or does anyone have a suggestion
> as a fix.

I would say that PDF's ought to be encoded base64 everytime. I also
wouldn't have thought that a PDF could survive being sent as

After a quick search on Google RFC 1521 states "The Quoted-Printable
encoding is intended to represent data that largely consists of octets
that correspond to printable characters in the ASCII character set." and
by my reckoning your average PDF file doesn't fit that description!

I also didn't think that MailScanner altered content of messages unless
it was told to because of some condition being met (striphtml or
something like that). The virus scanner should just be presented with a
copy of the attachment and asked if it's ok or not. I don't think that
the attachment is removed and then reattached in some way.

When you say you can turn scanning off and the quoted-printable PDFs go
through ok, is this (at least one of) the same q-p PDFs which gets

Not much help really am I?? ;-)



Martin Sapsed
Information Services               "Who do you say I am?"
University of Wales, Bangor             Jesus of Nazareth

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