Re: [exim] Return reciept on forward

On Sat, 24 Dec 2005, Giuliano Gavazzi wrote:

[quoting spamcop:]
> Although bounces are required, it is possible to avoid the situation
> under which they are required (see above). So they aren't really
> required unless you have already 'painted yourself into a corner.'"
>
> so, either you check recipient by attempting the delivery while
> still at SMTP phase (a nightmare with timeouts) or you forbid
> forwarding (an approach not totally without sense) or you send
> errors to postmaster (a nightmare on busy sites).

It all sounds plausible, but I'm afraid that our users would not stand
for a mail system which refused to implement forwarding, and vacation
responses. No matter how carefully we admins try to convince them
otherwise ;-)

We make every effort to avoid accepting spam in the first place, as
well as inhibiting the vacation response at the slightest indication
of bulk mail, mailing lists, etc. etc., anything that isn't a bona
fide personal email to the individual (I have argued that we should
also inhibit the vacation response at a spamassassin spam-suspect
score of 5.0, instead of at the rejection level of 8.0, although this
hasn't actually been implemented).

But, once we have accepted an item, some users will, as I say, have
set their options for forwarding and/or for a vacation response.
Verifying the forwarding address at SMTP time is all very well, but
there are also cases where we have accepted the item as non-spam, and
we only get to discover that the target MTA rates the content as spam
when we try to forward it. There can be other plausible circumstances
where we accept an item for forwarding, and only afterwards discover
that we are unable to deliver it. At this point, we're required by the
specs to compose a non-delivery report, and we can't really afford to
have each and every one of those vetted by the postmaster before it
goes out.

So yes, there will be some low level of bogus bounces from us, under
those hopefully limited number of circumstances.

We also have the situation where users have accounts at remote sites
with forwarding to us. Whenever we decide to reject items from those
forwarded accounts, the remote site is supposed to be composing a
non-delivery report - but that's done under the responsibility of the
forwarding site, and IMHO can't really be blamed on us. I've been
flamed on more than one occasion for rejecting unwanted items (such as
forwarded viruses, which caused the forwarding site to bounce the
virus to an innocent party and get themselves blacklisted), but I'm
afraid I've no sympathy for the idea that we're somehow morally
compelled to accept crud from these forwarding sites in order to help
them stay out of blacklists.

best regards and seasons greetings