Getting back to the original case of this, my personal beleief is that
"user mailbox full" should result in a 5xx error anyway. If my user is
trying to send mail to your user, and you have imposed a quota on your
user, why the heck should *my* MTA have to serve as a queue for your
over-quota user? Either say 5xx and let my user call yours on the phone
to complain about it, or accept the thing and queue it on YOUR server
until they clear out their mail.
On Fri, 12 Nov 1999, Philip Hazel wrote:
> On Thu, 11 Nov 1999, Phillips, Alan wrote:
>
> > Looking in Marshall Rose's SMTP book, the specified action for a 452 in
> > response to a RCPT TO is "retry later"; only if you get a 452 in response to a
> > MAIL FROM is it "try next server".
> >
> > Am I being dense in thinking Exim should back off after the first failure here?
> > I don't have the raw RFCs to check against....
>
> The raw RFCs are unspecific on this. The new version of RFC 821 (still
> coming ... slowly ...) says: "It is difficult to assign a meaning to
> 'transient' when two different sites (receiver- and sender- SMTP agents)
> must agree on the interpretation." That pretty well sums it up. In its
> comments about multiple addresses for MX records it says:
>
> When the lookup succeeds, the mapping can result in a list of alternative
> delivery addresses rather than a single address, because of multiple MX
> records, multihoming, or both. To provide reliable mail transmission, the
> SMTP client MUST be able to try (and retry) each of the relevant addresses
> in this list in order, until a delivery attempt succeeds. However, there
> MAY also be a configurable limit on the number of alternate addresses that
> can be tried. In any case, a host SHOULD try at least two addresses.
>
> That can be read as saying the client should try all the addresses.
>
> You have produced a case where trying the next server is sub-optimal. I
> can produce a case where it isn't:
>
> . There are two or more "equal" servers for a domain - that is, one is not a
> "backup" for the other, but each can handle mail for the domain all by
> itself without reference to any other(s). (The gateway servers to
> cam.ac.uk are like this.)
>
> . One of these servers gets its discs full, or some other similar
> problem, and so starts issuing 452 responses.
>
> In this case you *do* want to try the other server.
>
> --
> Philip Hazel University of Cambridge Computing Service,
> ph10@??? Cambridge, England. Phone: +44 1223 334714.
>
>
>
> --
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>
