In <[log in to unmask]> [log in to unmask] writes:
> > OK mail gurus, why do I get some mail with the text "=3D" or "=20"
> > interspersed in various messages? Is it the mailer, my mail reader,
> > 8 bit codes, viewing the screen at the wrong angle?
>
> It's the fault of the mailer used by the sender of the message.
>
> What is happening is that the receiving end (the SMTP server) is having to
> break the lines because they are too long.
>
> The mailer program (Microsoft Exchange) included with Win95 tries to send an
> entire message as a single line (!!). The receiving end doesn't like this
> much, and ends up breaking the lines, inserting the "=3D" and "=20" that you
> see.
>
> Microsoft seems to play hard and fast with the internet RFCs, breaking them
> where they feel like it.
In the case of the particular message mentioned, I believe Dan is correct
in that the message was chopped-up like that because MS Exchange wanted to
preserve the very-long input line lengths typical in GUI editors, and this
was the only way they knew to do this (in fact they did the correct thing,
though I have monitored conversations with the MS engineer in charge of that
particular code and they are re-thinking that option). The net-effect of what
they do means that it functions correctly for MIME-capable GUI mailers, but
looks REALLY ugly to non-MIME mailers, and doesn't work entirely well for
MIME-mailers viewing in fixed-length screens.
(I would note that the MS engineer responsible for the Q-P solution actually
did solicit input from the IETF working groups -ableit after the fact- and
did volunteer to fix it's behaviour. What they did was technically correct,
though it was not a good solution. He did receive several suggestions from
other vendors on how to better handle that situation. It was quite a
pleasant surprise to actually see a MS engineer solociting suggestions and
accepting critiques from the IETF people.)
The =<hex codes> in mail messages are in fact an encoding defined in MIME
as quoted-printable. The intention of this encoding is to allow the
transport of an occasional non-7-bit character within a mainly text message.
This was (mis) used by MS Exchange, but IS commonly used to transport
messages that contain foreign (non US) characters.
To quote one of the MIME RFC's:
"The Quoted-Printable encoding is intended to represent data
that largely consists of octets that correspond to printable
characters in the ASCII character set. It encodes the data
in such a way that the resulting octets are unlikely to be
modified by mail transport. If the data being encoded are
mostly ASCII text, the encoded form of the data remains
largely recognizable by humans. A body which is entirely
ASCII may also be encoded in Quoted-Printable to ensure the
integrity of the data should the message pass through a
character-translating, and/or line-wrapping gateway."
*If you view these message with a MIME capable reader, you'll never see
the hex codes; MIME viewers automatically decode the codes into printable
characters.
As mentioned, quoted-printable actually encodes "soft" and "hard" line
wraps (CR/LF sequences) in messages. QP (if you look at it "raw") is
always chopped off at less than 76 characters and "soft" line breaks are
added ("=" signs at the end of lines). "hard breaks" (CRLF or =0D=0A) are
inserted where actual end-of-lines should display. In MS Exchange's case,
a very long line would be encoded as several <data>= lines followed by
a <data>=0D=0A (where the actual line break should be displayed). MS needs
to rework their message editor (as I believe the engineer from MS stated
they are doing) to let users know that if they create very long lines, they
may be broken up at odd places by other mailers; and/or to allow the user
to force that long lines get sent intact (requiring quoted-printable on
the receiving end, AND a GUI interface capable of displaying arbitrarily
long lines).
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