Re: [Exim] When the lowest numbered MX is firewalled.

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Auteur: Philip Hazel
Date:  
À: JB
CC: exim-users
Sujet: Re: [Exim] When the lowest numbered MX is firewalled.
On Thu, 30 Aug 2001, JB wrote:

> I totally disagree. People have been using this kind
> of mail delivery for ages and it's also perfectly
> "legal" and correct to do so.. it may add a very small
> increase in work for the sending MTA but why should
> the receiver of the email ever care about this??


Why should anybody care about causing work for anybody else? Because
it's the friendly, cooperative thing to do. Despite the inroads of
commercialism, the Internet is still mainly a cooperative society. That
is one of its strengths.

I'm not sure about "legal" and "correct" either. There's nothing
explicit in RFC 2821, but it is clear from reading it that the
expectation is that if an MX record points to a host, then that host is
normally accessible for receiving mail.

What on earth is the point of pointing an MX record at it otherwise?
It is just gratuitously making other MTAs waste time and resources.

If I get time, I will do some further searching in the RFCs and other
places. And I will also ask the author of RFC 2821 for his opinion.

Philip

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.