On 19/12/2019 10:58, Jeremy Harris wrote:
On 19/12/2019 09:46, Peter J. Holzer wrote:
I vaguely remember that there was a draft for an extension where the
server could communicate a hold time to the client. Something like "try
again in 5 seconds" for too many recpients or "try again in 24 hours"
for a full mailbox.
There was https://tools.ietf.org/html/draft-santos-smtpgrey-02
but I don't think it gained traction.
That is actually mildly widely used. There are MTA clients which look
for hints in a 4xx response to decide when to retry and the
'retry=hh:mm:ss' text is one of the hints they look for.
It's a trivial-effort thing for a server to implement, and
not-much-more-effort thing for a client to implement if it can already
handle different per-message retry delays.
But it was designed to 'optimise' greylisting, so may not be useful for
this scenario (but it may be - after all, the client can't always work
out WHY the message was temp rejected).
--
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