Re: SMTP Transferred-By-Reference

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:<joe(_at_)example(_dot_)com> SIZE=10000000
S: 250 Ok
C: RCPT TO:<jane(_at_)example(_dot_)net>
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],
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