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Re: [ietf-822] "--" first in lines to indicate start of signature

2016-01-04 12:33:49
On 1/4/2016 8:39 AM, Jacob Palme wrote:

On 3 jan 2016, at 00.05, Murray S. Kucherawy wrote:

What other uses of "--" on a line by itself are there?  The only thing I can 
think of is ASCII art.

I have used "--" to separate sections in a longer plain text document. I have learned to not use it 
in that way in mail messages, and use "==" instead of "--". But it is a simple mistake to 
make if you are not aware of its special meaning in mail messages. Which probably many mail users are, 
everyone is not an expert on mail protocols, as we who subscribe to this mailinglist are.

Jacob, since the 80s, I've written a number mail reader/writers, a.k.a. MUAs, mail tossers, importers/exporters, gateways/mailers, etc for several networks and mail formats where each had its own technical relationship to body parts such as "tear lines" and "Origin" lines, and/or kludge lines.

For the old school Fidonet mail network, the Fidonet Technical Standards provided early guidelines.

(I was looking for a specific one that also described the tear line with line information, I couldn't find it offhand.)

Many IETF folks has a history with Fidonet. I recall FSC-0046 was JoHo's attempt to add "commercial tagging" using a PID (Product ID) kludge line because of the Tear Line and Tag line "Stripping Wars." The proposal tried to give some guidelines for mail product developers to follow at the time. I recall the "Stripping Wars" when some product vendors began to add/strip/replace the tear line with "--- Not Registered" tags and other mail products and even operators stripped and replaced it with there own tags during the transport process. In fact, to illustrate the problem, I added logic in a MUA to completely hide them and/or replace it with a "visual" change, not a physical mail storage change. Call it Visual Tampering! It goes to show how young MUA technology is still is because it is ultimately the tool that people use to SEE the mail with.

Also, there are other "formats" for this, three dashes "---" and "Origin Line" style " * " that FSC-0043 describes. Add the QWK tag line, its possible to see 2-4 lines:

--  User Line, maybe.
--- Mail Product Line
 *  Original Domain line

Look at the line that the iPhone and iPad adds to each message automatically. There is no rule that says it has to remain there. :)

At the end of the day, we don't have control over the body nor what the MUAs wants the user to see. But I agree, the Mail Creator, the MUA, should probably have some RFC5322 related guideline on what to use. When the move was made to RFC 822/2822 several decades ago, I wasn't aware of any "IETF guideline" for this. There is probably some I-D or RFC proposal now or someone can come up with one but overall, if it begins to get exploited with overhead text, commercialization concepts, etc, its going to get stripped and "visually" hidden. :) Just consider that new mail viewing devices doesn't have the real estate for such overhead.


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