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

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Συντάκτης: Ceri
Ημερομηνία:  
Προς: JB
Υ/ο: exim-users
Αντικείμενο: Re: [Exim] When the lowest numbered MX is firewalled.
On Thu, Aug 30, 2001 at 05:43:12AM -0700, JB said:
>
> 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 I care if everyone with blonde hair gets run over by
a bus ?
Because it's not very nice for them, that's why.

> It can also add greater resilience and flexibility in
> adding and removing servers as you can add multiple A
> records relating to the server recv.mail.com.


You can do that anyway.

> Just because the above configuration may be classed as
> "annoying" doesn't make it wrong!


No, sorry - it's wrong.

An excerpt from RFC 974 :
If the list of MX RRs is not empty, the mailer should try to deliver
the message to the MXs in order (lowest preference value tried
first). The mailer is required to attempt delivery to the lowest
valued MX.

An excerpt from RFC 1034:
                MX              a 16 bit preference value (lower is
                                better) followed by a host name willing
                                to act as a mail exchange for the owner
                                domain.


If you don't want people to try to send mail to gw.mail.com, then don't
put it in the MX RRs for the zone.
That doesn't mean that recv.mail.com can't forward every mail it gets to
gw.mail.com - this concept is called a ``mail hub''.

We implement this at our ISP - it's unreasonable to expect everyone else
on the internet to waste time trying to send mail to a host that will not
accept it, especially when exim makes it so easy to do it properly.

Ceri

--
Your local RFC Nazi