On Sun 23/Jul/2023 22:12:55 +0200 Barry Leiba wrote:
Without bounces the sender is in the dark.
Yes, if the sender is a human.
Not so, if the sender is a mailing list and that sender will then
unsubscribe the intended recipient.
Also not so, if the sender is a malfeasant who may use the bounce
message for bad purposes.
It's very clear to me that if I think a bounce message will be
harmful, I will not send one. I will happily prefer silent discard
over a bounce when I think that's a better approach for that
situation. Bouncing a legitimate mailing list message is just bad.
If you have reason to believe you're going to do that... don't.
Either deliver the message or silently discard it. But don't bounce
it.
Living aside the malfeasant case for a moment, do you think the worthiness of
bounces can be stated depending on the type of sending? Always?
The only meaningful signal a mailing list can get out of a 5xx response is to
deduce that that mailbox doesn't exist any more, so it must be unsubscribed.
For alias expansions, there is the case that the author can appreciate to learn
that her correspondent's mailbox is full, or that her writings was considered
spam. But again, consider that friends most likely write directly to the
target mailbox, while newsletters deserve the same treatment as mailing lists.
Is List-Unsubscribe: an indicator of drop vs. reject?
Best
Ale
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