Rejecting some recipients after DATA?

Brian J. Murrell
Sat Apr 20 22:05:20 UTC 2002

On Sat, Apr 20, 2002 at 03:39:46PM -0600, Vernon Schryver wrote:
> I hope "disaster" is too strong,

Maybe it is, maybe it's not.  I think there are all kinds of
subjective conditions that turn "yucky" into "disaster", like for
instance maybe the mail that got dropped was for the CEO.

> because at least some of the mail
> gets through and because the message is logged for those not whitelisted.

Maybe this will prevent "yucky" from turning into "disaster".  This
logging of mail that is bulky but not whitelisted is a dccm feature
IIUC?  I have only been using the dccproc interface (and not dropping
any mail yet) so maybe that's why it would look disasterous to me at
this point.

> What alternative is there?  On a non-trivial system you cannot
> reduce the "recipients buffer" to 1 even if don't care that
> page 55 of RFC 2821 demands 100.

I agree absolutely!  The resource wastage to handle single recipients
only is unacceptable.

> You can't partially succeed or
> fail on the DATA command.

Right.  This is the crux of it all.  An SMTP extention that did allow
a success/failure PER recipient would be nice.

> It would be worse to reject the message
> for everyone, because you know at least some recipients want it.

I know.  I agree with all of your points.  I am hoping we can come up
with a workable solution.

> Exactly.

Sounds like the ticket.  Now to just do it.  :-)

> I don't think sendmail would need or could use such a command line
> mechanism,

Indeed not.  But it would be nice for the admin.  I just want to be
able to "reuse" Sendmail's DSN bounce code.

> but it seems to me that it would fit nicely with the Milter
> interface.

I am not familiar with Milter because I don't have Sendmail listening
on port 25.  Like others here, I don't trust it enough.  I use a
hacked versio of Obtuse' SMTPD as well.

> (I'm really trying to not think of the obvious solution of having
> dccm generate the DSN.)

Or dccproc, or just an external utility in general.  I have already
been searching for a "mail message in, DSN bounce out" type
filter/utility.  I don't see one yet.  It surprises me that I have not
found a Perl module on CPAN actually.

> One of the reasons I'm trying not to think that unthinkable thought is
> that I've recently seen Internet-Drafts about DSNs.  I fear DSNs are an
> infinitely deep and wide swamp and best handled by someone, anyone else.

RFC 1892 and 1894?  I have not read through 1894 all the way, and it
does look longish, but I doubt every case in there applies to us.


Brian J. Murrell
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