On Sun, 25 Jun 2023 14:28:33 +0100, Dmytro Homoniuk via mailop
<[email protected]> wrote:
>*In a very non-confrontational way* I want to express my opinion and to
>note that's pretty much how senders operate right now: too often the smtp
>code and enhanced code the recipient system returns have nothing to do with
>what the response text says - and every mailbox provider uses their own
>flavor to boot.
My favourite is a particular immense mailbox provider that is known to issue a
4xx code with text that basically says "This is a permanent temporary failure;
retries will never succeed."
Looking for design intent in this phenomenon, one possible objective
immediately comes to mind:
If you consider the sender to be hostile, issue permanent tempfails so that,
if the sender has used a default (long) queue expiration time in their sending
software, one can keep a full day or more of re-queued messages on the
sender's system, perhaps blowing out the system's disk space, and causing
other sending performance issues that reduce the spammer's ability to spam. I
have seen these effects in more than one system in the wild.
mdr
--
"There are no laws here, only agreements."
-- Masahiko
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