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-----Original Message-----
From: Uncle George [mailto:qmail@gatworks.com]
Sent: Tuesday, November 28, 2006 2:48 PM
To:
Cc: qmail@list.cr.yp.to
Subject: Re: Qmail is clearly out of compliance with RFC2821
> So qmail MUST try multiple alternative addresses. And in effect IT DOES
> THAT (if connection cannot be established).
"So qmail MUST try multiple alternative addresses" - until the message
is successfully accepted. Qmail does not do this for all cases on which
the message is not accepted.
>
>>> specific installations may want to limit or disable the use
>>> of alternative addresses.
>>
>> I believe what it means here is that the capability is required but you
>> might want to put limits on it because of resources.
>
>
> I believe what it means here is that the capability can be subjected to
> policy restriction. For qmail, policy rules are:
> - if a connection cannot be established, try next MX.
> - if a connection succeeds, but server is unable to accept transaction,
> don't try next MX.
Unfortunately, its not for qmail to decide policy. Its up to the admins,
air-head management, and yokels to deceide for them selfs what the
policy restrictions should be. Once the "try all MX's" requirement is
implimeted, then administratively the try all mx's can be reduced to
just 2. I suspect that the limit can be further reduced to 1.
> Compliant.
>
>>> The question of whether a sender should
>>> attempt retries using the different addresses of a multihomed host
>>> has been controversial. The main argument for using the multiple
>>> addresses is that it maximizes the probability of timely delivery,
>>> and indeed sometimes the probability of any delivery; the counter-
>>> argument is that it may result in unnecessary resource use.
>>
>> This is what lawyers cal dictum. It's a discussion. The reason for
>> trying all MX is timely delivery. The exception is resources. If for
>> example you are running your server on a dialup connection at 56k you
>> can make an exception because retries use up your limited bandwidth.
>
>
> "The main argument ... is", so it's not the only argument. Another
> argument may exists: so "if the main server is up, try only that server
> because sending message to the final recipient is faster" is another
> good argument. Counter-argument is "but if sysadmin screwed it's
> configuration, misused protocol, activated brain-dead anti-spam
> measures, it will not receive the message" ...
I suppose the point here is that the sysadmin would/should be fired?
Clients would move onto other organizations that sysadmin better? etc.
Darwin had something to say on this subject.
Both MUA and MTA have administative choices in how the facility should
run. If the MTA does not want all the servers hit, then limit the number
of published MX's. If the MUA does not want to try all the MX's, then
set the limit to (min) 2.
BTW: if "you are running your server on a dialup", then you probably
have only one MX, and this discourse becomes academic.
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