Re: Processing after the end of DATA
2010-08-11 14:50:21
Dilyan, We are getting way off topic for this list, so I invite you and
anyone else who is interested, to a continuation of this discussion at
http://groups.google.com/group/registry_internet.
Дилян Палаузов wrote:
>
> On 10.08.2010 20:18, David MacQuigg wrote:
>> My system is too small to draw any conclusions, but my impression is
>> that we are overly-concerned about a very small fraction of the mailflow
>> - those few messages that are legit, but get a false reject from a
>> statistical filter. We really don't care about the proper SMTP response
>> if it is spam. The only advantage I see in running the spam filter
>> before ACCEPT is a few less messages at the bottom of my spam bucket. I
>> wish I had some numbers from a larger system.
>
> A user might have installed redirect for her incoming mails to
another mail provider. The other provider might SMTP reject incoming
spam. If there is spam for your user, your server does accept it, then
sends it to the other mail provider, and that second server SMTP rejects
it, then your server will have to send DSN for that SPAM (provided that
you do not want to discard emails). With rejection-preferences similar
on both servers, the amount of such DSNs will decrease, when both
servers reject after DATA. You have no influence on what other servers
do with the spam (smtp rejecting or inserting in spam folders).
We have quite a bit of influence. We insist that our recipients turn
off all spam filtering, chain-forwarding, SPF checks, whatever might
conflict with our acting as Receiver for their box67.com email address.
Typically, they will have a private mailbox known only to our
Receiver/Forwarder. Failures resulting from SMTP rejects, DSNs, or any
other problem at the recipient's mailbox are treated the same as a
mailbox being suddenly offline. Incoming mail to that address is
rejected until we can resolve the problem with the recipient.
>> Would be nice if SMTP had a 'conditional ACCEPT': "Sorry, your
>> transmitter ID 'yahoo.com' cannot be verified, Your message has been
>> routed to the recipient's quarantine." Imagine the effect that would
>> have on all the lame excuses for an invalid or hard-to-verify HELO name.
>
> What do you want to communicate to the sender with this conditional
ACCEPT: "Dear Sender, your suspicious email has arrived. It might be
read soon, it might be read late, or it might not be read at all."?
No, the message I suggested had a specific reason for the failure. It
should also have a link to a webpage with instructions on how to fix the
failure, like what we have now on REJECT messages:
http://open-mail.org/3strikes/REJECT.html
> The problem with the spam folders are the false positives. Many
users do check the spam folders/quarantines not that often as their
Inbox and with less attention. This might lead to reading a message too
late, or even overseeing it. I prefer to immediately notify the sender
that her message was not delivered, including in the SMTP response
alternative ways to contact the recipient (and spamassassin-evaluation
of the mail), rather than let the sender hope that her email was
properly delivered, while there is a risk that the recipient oversees
that message.
False rejects are indeed the main problem with modern email systems, but
this problem isn't solved by rejecting a small fraction of messages with
the highest spam scores. There are still plenty of messages, almost all
spam, that get a score low enough to be kept in quarantine, and there is
always a risk that the recipient will overlook a legitimate message.
The only good solution to the false reject problem is to offer senders a
way to avoid the statistical filters entirely. That is what a
reputation system does. When a message comes from yahoo.com (or any
other A-rated domain), it goes straight to our recipient's inbox.
************************************************************ *
* David MacQuigg, PhD email: macquigg at ece.arizona.edu * *
* Research Associate phone: USA 520-721-4583 * * *
* ECE Department, University of Arizona * * *
* 9320 East Mikelyn Lane * * *
* http://purl.net/macquigg Tucson, Arizona 85710 *
************************************************************ *
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- Re: Processing after the end of DATA, (continued)
- Re: Processing after the end of DATA, SM
- Re: Processing after the end of DATA, Nathaniel Borenstein
- Re: Processing after the end of DATA, David MacQuigg
- Re: Processing after the end of DATA, Carl S. Gutekunst
- Re: Processing after the end of DATA, David MacQuigg
- Re: Processing after the end of DATA, John Levine
- Re: Processing after the end of DATA, David MacQuigg
- Re: Processing after the end of DATA, Дилян Палаузов
- Re: Processing after the end of DATA,
David MacQuigg <=
- Re: per user post-data rejects, Processing after the end of DATA, Дилян Палаузов
- Re: per user post-data rejects, Processing after the end of DATA, David MacQuigg
- Re: per user post-data rejects, Processing after the end of DATA, Дилян Палаузов
- Re: Processing after the end of DATA, ned+ietf-smtp
- Re: per user post-data rejects, Processing after the end of DATA, John Levine
- Re: per user post-data rejects, Processing after the end of DATA, ned+ietf-smtp
- Re: per user post-data rejects, Processing after the end of DATA, Dave CROCKER
- Re: per user post-data rejects, Processing after the end of DATA, Carl S. Gutekunst
- Re: per user post-data rejects, Processing after the end of DATA, ned+ietf-smtp
- Re: per user post-data rejects, Processing after the end of DATA, Nathaniel Borenstein
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