[107529] in North American Network Operators' Group
SMTP rate-limits [Was: Re: ingress SMTP]
daemon@ATHENA.MIT.EDU (Paul Ferguson)
Fri Sep 5 04:38:11 2008
From: "Paul Ferguson" <fergdawg@netzero.net>
Date: Fri, 5 Sep 2008 08:36:10 GMT
To: simonw@zynet.net
Cc: nanog@nanog.org
Errors-To: nanog-bounces@nanog.org
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- -- Simon Waters <simonw@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 rat=
e =
limits. Otherwise if they send all email from their users, all they've d=
one
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 (?).
=2E..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/
