On Thu, Jun 1, 2023 at 11:20 AM Alessandro Vesely via mailop <
mailop@mailop.org> wrote:
> On Thu 01/Jun/2023 17:45:38 +0200 Robert L Mathews wrote:
> > So I guess it's time to add SRS rewriting for Gmail addresses...!
>
>
> The only points I see in SRS are mailbox full or oversize. You ought to
> notify
> the author that the message got lost. It is just a temporary feature,
> though.
>
> But this does not happen so frequently any more. Disk space went cheaper
> and
> cheaper, and mailbox limits are not so tight any more. Permanent
> failures,
> 5xx, are permanent, like cancelled account. In that case, SRS doesn't do
> a
> good job. It is better to remove the forwarding instructions completely,
> no?
>
I feel like SRS is trying to be something more than just VERP, but the more
was never really flushed out.
The "more" is validation that you generated the address, so you can ignore
mail that isn't actually a bounce... perhaps if
it starts getting spam or whatever.
The issue is that bounces may occur after days, so you would need to make
your address usable for days. And you might get
transient bounce messages ("still trying"), or the next hop may not rewrite
and forward to multiple addresses...
Anyways, most folks seem to be fine with just a less validated approach, up
to them.
Gmail's forwarding has always used a VERPs like approach with the +=caf
semantics, and yes, repeated bounces of certain types
can lead to the forwarding being disabled... though, there's obviously
issues with stopping forwarding because customers may never
be checking the forwarding account.
Also, 5xx means permanent failure just for that transaction, not for the
account ever... though one can try and deduce whether the latter is true.
Anyways, obviously folks who forward should not respond to the sending
server until the message has been accepted by the forwarding server, and any
smtp rejection should be propagated directly to the sender... oh, and spam
check before even attempting to forward, of course.
Brandon
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