There is nothing to prohibit sending multiple HELO/EHLOs.
Any logic applied to restrict it would be strictly local policy based. Some
systems might have an input limit, lets say 3-5 times most?
But lets look at how its possible or why it is was allowed:
From an automated sense: There is no reason for it.
From a manual sense, humans are prune to typos.
Most of the conversation based protocols where developed with HUMAN based
debugging capabilities - i.e., telnet, console applications. There is was
no computer based reason for the layman, higher overhead, text based
client/server command line driven conversation protocols.
So imagine the days when the Dave Crockers were writing this stuff with a
VT100 or Dumb terminal and all they had an console based interface to create
and test these commands. He types:
HELO mahine1.com
451 server.com, why do you call yourself mahine1.com?
And decides....
"hmmm, typos are possible, lets relax it and allow reentry"
HELO mahine1.com
250 server.com, why do you call yourself mahine1.com?
HELO machine1.com
250 server.com, please to meet you machine1.com!
This kind of mentality was (and still is) par for the course.
Just an insight to explain why it is and how it could of come about. :-)
---
Hector
----- Original Message -----
From: "Frank Ellermann" <nobody(_at_)xyzzy(_dot_)claranet(_dot_)de>
Newsgroups: spf.-.sender.policy.framework.discussion
To: <spf-discuss(_at_)v2(_dot_)listbox(_dot_)com>
Sent: Saturday, February 18, 2006 9:19 AM
Subject: [spf-discuss] Re: multiple HELOs
paddy wrote:
Is it possible to have a first HELO accepted, a second one
turned down and then proceed to MAIL FROM ?
Beats me, test it. Multi-HELO appears to be rather abnormal
if I got Ralf's drift. The last accepted HELO could be still
"the" HELO. It won't surprise me if different servers have
their own ideas about multi-HELO.
Bye, Frank
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