On Sun, 26 Feb 2023 10:34:11 +0000, Laura Atkins via mailop
<mailop@mailop.org> wrote:
>If people intend to be interoperable, there is NO variation in what a 4xx and
>a 5xx mean.
>
>4xx means: this message can be queued and retried at a future date.
>
>5xx means: this message cannot be retried without human intervention.
>
>Those interactions are defined in RFC 821 and itÂ’s successors. [1]
>
>The variation / confusion / problems / conflict comes when we try and use
>these very clear *transactional* signals to interpret what to do with a
>different and future message to the same address.
>
Then there's the Y! "4xx -- deferred, but retrying anything from this IP will
never succeed" message. I speculate that this is in place to encourage the
spamming system to retain the messages to help blow out its queue space and
slow things down considerably. Think of it as implicit rate limiting, while
increasing the senders' costs.
mdr
--
If I laugh when a guy goes flying on a banana peel, is that a
schadenfreudian slip?
-- Zippy
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