Stealth Blocking

Eric A. Hall ehall at
Thu May 24 17:23:23 UTC 2001

Dave Rand wrote:

> I'm not sure how effective rate limiting will be.  Many spammers send
> one copy of the spam to an open relay, but use many (2 to 50)
> recipients.

Rate-shapers would also work on the relays. The idea is that if ISPs would
implement a default rate-limit (let's say 4kb/s) that it wouldn't
interfere with normal use. It would interfere with spam distribution
because it would slow down the big runs dramatically.

The negative side effect is that it cripples people who use email as a
file transfer protocol.

> One other way to do this might be to do port 25 blocking on new
> customers, but allow customers to get unblocked on request after
> they have been  around a while...

That would be nice as well and is something I've advocated. ISPs seem
unwilling to do this, and it would seem that implementing a default
low-bandwidth rate limit would mean less maintenance.

Eric A. Hall                              
Internet Core Protocols

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