Re: [ietf-smtp] Stray <LF> in the middle of messages

Keith Moore <> Wed, 10 June 2020 11:33 UTC

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From: Keith Moore <>
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Date: Wed, 10 Jun 2020 07:33:03 -0400
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Subject: Re: [ietf-smtp] Stray <LF> in the middle of messages
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On 6/8/20 10:03 AM, Hector Santos wrote:

> Maybe because at that point in time, Microsoft had owned 90% of the 
> growing Personal Computer (PC) market.  The Mac was still considered 
> (legally) a luxury commodity (otherwise their anti-trust status would 
> no longer apply), and *nix was still mostly at the IT networking level.

The CRLF convention for transfer of Internet text files (in FTP, which 
was the first protocol used to send email on the ARPAnet), predates the 
existence of both PC-DOS and MacOS by several years.   I am guessing 
that FTP got its end-of-line convention for text files from TELNET.

Of the systems in use on the early ARPAnet, I have read that TOPS-10 
supported CRLF as line terminators.  I recall correctly from some of the 
early RFCs listing ARPAnet hosts (back when the ARPAnet was small) 
TOPS-10 systems were a bit more widely represented than others.   But I 
don't know how much this had to do with the selection of CRLF.   There 
were very many conventions in use for representation of text files, and 
some systems even supported multiple representations and even multiple 
sizes for characters (5, 6, 7, 8, or 9 bits) on the same system.

CRLF also may have had an advantage in that text files using that 
representation could be sent directly to an ASCII terminal (like a 
teletype or CRT) or printer without the need for translation.