SMTP rate-limits [Was: Re: ingress SMTP]
Paul Ferguson
fergdawg at netzero.net
Fri Sep 5 08:36:10 UTC 2008
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- -- Simon Waters <simonw at zynet.net> wrote:
>If the ISP blocks port 25, then the ISP is taking responsibility for
delivering all email sent by a user, and they have to start applying rate
limits. Otherwise if they send all email from their users, all they've done
is take the spam, and mix it in with the legitimate email, making spam
filtering harder.
>
Okay, I can understand why an ISP might want to apply SMTP
rate-limits, but to clarify, I'm assuming you meant that ISPs
(if they do block tcp/25 outbound to anything other than their
own MTAs) need to watch for excessive SMTP utilization, which might
indicate a spammer-client (?).
...as opposed to arbitrary SMTP rate-limits.
Yes?
- - ferg
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--
"Fergie", a.k.a. Paul Ferguson
Engineering Architecture for the Internet
fergdawg(at)netzero.net
ferg's tech blog: http://fergdawg.blogspot.com/
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