exim question

Vernon Schryver vjs@calcite.rhyolite.com
Wed Jul 14 15:43:23 UTC 2010

> From: Paul Vixie 

> i think it's something sendmail just did, and that others have emulated.

Maybe the original was a de facto standard from sendmail, but the
official IPv6: tagging standard in RFC 2821 is about 10 years old and
is widely followed.  There's even an IANA registery for address literal
tags, although it lists only IPv6.
I don't know why the IPv6: tag was thought necessary.  Maybe it appeared
during the early confusion about how to represent IPv6 addresses.

> > Parsing Received headers is always dodgy, because it was never intented
> > to be machine readable.
> that's what i thought too, but there is a grammar and they are indeed meant
> to be machine readable.

It's too bad so few pay attention to official or de facto standards,
but are compelled to prove their creativity in such obscure ways.
Why couldn't the HTTP/HTML people use the same scheme as SMTP
or vice versa?   RFC 2732 and RFC 2821 conflict.

I don't want to think about those who are serious about Received: header
parsing do.  This is my current list of recognized forms:

/* find IP address, client host name, and HELO string in a Received:
 *	    header of forms:
 *  #1	Received: from helo (hostname [addr] ...
 *	Received: from helo ([addr] ...
 *  #2	Received: from hostname [addr] ...
 *	Received: from  [addr] ...
 *  #3	Received: from qmailheloandhostname (addr) ...
 *  #4	Received: from qmailhostname (HELO qmailhelo) (addr) ...
 *   or	Received: from qmailhostname (HELO qmailhelo) ([addr]) ...
 * ignore these forms:
 *  #5	Received: from localhost by hostname with LMTP
 *  #6	Received  (qmail 4824 invoked by uid 1000); 8 Nov 2005 12:13:33 -0000
 *  #7	Received: (qmail 21530 invoked from network); 29 Aug 2005 16:05:04 -0000
 *  #8	Received: (from user@localhost) by lochost (8.12.10/8.12.10/Submit) ...
 *  #9  Received: by hostname (Postfix) id ...
 *  #10 Received: by hostname with SMTP id ...

Vernon Schryver    vjs@rhyolite.com

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