On 2007-11-13 18:32:49 -0800, Douglas Otis wrote: > For ISP that host customers sending out a spam campaign, their > servers may receive a temp error at that point in time. > Unfortunately, this may cause some desired email to be delayed. Once > spamming from that server ceases, normal acceptance is restored. > This dynamic reputation tactic blocks often more than twice the > amount of spam stopped by static lists. Graduated dynamic lists are > available to suit the needs of different receivers. > > Blocking an influx of spam using the temp error tactic frees up > resources needed to process other (cleaner) sources of email. > Simultaneously offering the TBR extension within the 451 4.7.8/9/10 > temp error would provide the transmitter a means to immediately > complete their transaction by reverting to the TBR mode. (Fewer > transactions and less delay.)
If I understood this correctly an SMTP server supporting TBR may return a 451 return code with any of the 4.7.8-10 enhanced status codes if it is currently unable (or unwilling) to accept email content (e.g., because of high load, a full queue, etc.) but is able to accept a TBR command. A client supporting TBR may then store the mail content on a webserver and send the TBR command with the URI: C: EHLO client.example.com S: 250-server.example.net S: 250-SIZE 20971520 S: 250 TBR C: MAIL FROM:<[EMAIL PROTECTED]> SIZE=10000000 S: 250 Ok C: RCPT TO:<[EMAIL PROTECTED]> S: 250 Ok C: DATA S: 451 4.7.10 Load too high - try TBR HTTPS mode (client saves the 10 MB message on _tbr.example.com) C: TBR 0 https://_tbr.example.com/1234567890abcdef S: 250 Ok I didn't understand this while reading the draft. You may want to clarify section 6. hp -- _ | Peter J. Holzer | It took a genius to create [TeX], |_|_) | Sysadmin WSR | and it takes a genius to maintain it. | | | [EMAIL PROTECTED] | That's not engineering, that's art. __/ | http://www.hjp.at/ | -- David Kastrup in comp.text.tex
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