Re: [Exim] Reaction to rude 554 greeting

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Autor: Exim Users Mailing List
Data:  
A: Florian Weimer
CC: exim-users
Assumpte: Re: [Exim] Reaction to rude 554 greeting
[ On Tuesday, March 18, 2003 at 11:29:36 (+0100), Florian Weimer wrote: ]
> Subject: Re: [Exim] Reaction to rude 554 greeting
>
> Matthew Byng-Maddick <exim@???> writes:
>
> > With issues like this, I'm not so completely sure. I think that all
> > in all 821 is a better standard. I think that returning 554 as a
> > greeting on a public-facing MX is probably pretty stupid. Giving an
> > RST is so much better.
>
> The BSD sockets API doesn't allow for sending a RST to selected peer
> addresses. You have to accept the connection to get the peer address.


Who says you have to do it from the listening socket?

(while I think you could do it via libpcap to a BPF, the obvious way is
to do it from a firewall, even a host-based one with IP Filter, etc.)

> And the practical consequences of an RST and a 554 opening message are
> quite different. 8-)


Especially if your connecting clients treat 554 properly! ;-)

I really fail to see any valid reason why a mailer would ever send
anything but 220 or some 4xx response after successfully accepting a
connection. This whole idea of documenting any 5xx response to a
connection is really stupid and unnecessary. Obviously all it has done
is allow inexperienced people to misuse it terribly wrongly. Yet
another example of how ill-thought-out many parts of RFC 2821 are.

--
                                Greg A. Woods


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