misunderstanding scale, SMTP edition

Tony Finch dot at dotat.at
Wed Mar 26 17:36:38 UTC 2014

John Levine <johnl at iecc.com> wrote:
> If I were a spammer or an ESP who wanted to listwash, I could easily use
> a different IP addres for every single message I sent.

Until mail servers start rate-limiting the number of different addresses
that are used :-) You can do something like the following in Exim, which
limits IPv6 senders to 16 addresses per /64 per day.

    hosts = <; 2000::/4
    ratelimit = 16 / 1d / per_conn /\
      unique=$sender_host_address /\

f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
Shannon, Rockall: Southerly 5 or 6 at first in west, otherwise variable 3 or
4, becoming northeasterly 4 or 5. Moderate or rough. Showers. Good,
occasionally moderate.

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