At 5:18 +0530 2003/03/17, Suresh Ramasubramanian wrote:
>On Monday, March 17, 2003 3:09 AM [GMT+0530=IST],
>Jason Robertson <jason@???> wrote:
>
>> Correct me if I am wrong, but if I remember my RFC's correctly doesn't
>> all 5xx errors refer to a permanent error?
>>
>> Personally if I find a host that is blocked trying to connect to all
>> my mail servers, they get both listed in the firewall rules, and are
>> null routed.
>
>5xx mostly demands that if you retry, do so later, *manually*. What it
>does say is that the remote domain refuses to accept delivery of the
>current message.
>
what current message? [BTW, the connection might have been just a
sender/callout verify]
I am sorry, but until the intention of delivering a message has been
stated, the error cannot mean that the domain refuses to accept *the*
delivery.
55X indicates a Mail System Error (see RFC) and specifically
"indicate the status of the receiver mail system", and, I repeat, 554
- I quote - in the case of a connection-opening response, "No SMTP
service here".
ALSO:
If MX records are present, but none of them are usable, this situation MUST
be reported as an error.
and few lines down:
To provide reliable
mail transmission, the SMTP client MUST be able to try (and retry)
each of the relevant addresses in this list in order, until a
delivery attempt succeeds. However, there MAY also be a configurable
limit on the number of alternate addresses that can be tried. In any
case, the SMTP client SHOULD try at least two addresses.
so, you report an error when none of them are usable and you should
at least try two, until you succeed; a server responding with "No
SMTP service here" is not usable in my book. Draw your conclusions.
Have you or Greg quoted anything from the RFC to support your
arguments? I admit the RFC might sometimes be inconsistent, but in
this case I have yet to find a fault.
Thanks
Giuliano
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