Re: [Asrg] What are the IPs that sends mail for a domain?

Lyndon Nerenberg <lyndon@orthanc.ca> Wed, 17 June 2009 16:21 UTC

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Date: Wed, 17 Jun 2009 10:21:17 -0600
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Subject: Re: [Asrg] What are the IPs that sends mail for a domain?
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On Wed, 2009-06-17 at 09:59 -0400, Paul Russell wrote:
> > Sure, it is the the be strict in what you send, lenient in what you
> receive.
> 
> The first part of that has always been a good idea.  The second part
> may have
> been workable ten years ago, but on today's Internet, exercising
> leniency in
> what you accept will get you flooded with all sorts of traffic that
> you neither
> want nor need.

"... be lenient in what you receive" *never* meant you should accept and
attempt to second-guess the intent of anything in violation of the
applicable protocol spec. It meant "don't tip over and die when
presented with crap." I.e., fail gracefully.

This was very important on things like the IMPs when the protocols and
their implementations were immature. It's still important today, but
only when interpreted with its original meaning and intent.

--lyndon