Date: Wed, 17 Nov 1999 21:08:13 +0000 From: Mark Ovens <mark@ukug.uk.freebsd.org> To: James A Wilde <james.wilde@telia.com> Cc: freebsd-questions@freebsd.org Subject: Re: Corruption of file attachments passing late BSD relayers Message-ID: <19991117210813.B316@marder-1> In-Reply-To: <015a01bf30e8$1c8298d0$8c0aa8c0@hk.tbv.se> References: <015a01bf30e8$1c8298d0$8c0aa8c0@hk.tbv.se>
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On Wed, Nov 17, 1999 at 11:40:03AM +0100, James A Wilde wrote:
> Digest: This message reports on the corruption of file attachments
> in messages passing certain BSD UNIX mail exchangers. The
> corruption affects messages sent using Microsoft Outlook and
> Outlook Express mail clients. It may affect other clients also
> The corrupted file attachments are about 30% larger than the
> non-corrupted form. A small part of the increase appears to be the
> insertion of CRLF at 76 character intervals. I have reported this
> as a bug to FreeBSD.org but one of low priority.
>
This is not corruption. M$ proprietry files are binary so they are
being uuencoded (which maps 3 bytes into 4 so that all bytes can
be represented in printable chars). This explains the 30% increase
in size and the CR/LF's as uuencode also splits the resultant file
into fixed length lines. All you need is to uudecode(1) them.
Netscape can do this and I'm sure that even M$ mail readers can as
well; we have a mix of Unix and M$ (Outlook) systems at work and
passing binary attachments poses no problems.
``man 5 uuencode'' for details of the algorithm used.
As an aside, a customer mailed me a text file the other day, that
was ~400K, as an attachment using M$ Exchange. By the time I got it
it was >800K (this file would Zip down to <100K). Seems that Exchange
embeds the fonts for RTF into the attachment that gets renamed
winmail.dat.
[snip]
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