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Re: Processing after the end of DATA

2010-08-11 12:25:41


if rejecting after CRLF.CRLF is better than bouncing, what about discussing draft-hall-prdr-00 and doing it more normative?

For an email with two recipients, the first one of who wants to receive the mail and the second -- not, there is currently no option but to say 250 OK after CRLF.CRLF and send later DSN. With the idea described in draft-hall-prdr-00, it is possible to avoid the currently unavoidable DSN. Any suggestion, how this draft can be revived?

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).

Would be nice if SMTP had a 'conditional ACCEPT': "Sorry, your
transmitter ID '' 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."?

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.

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