On Wed, 10 Jul 2002, Rich Lenihan wrote:
> I'm probably being really dense this morning, but "whaaaaaat??????"
> Please explain to me again why using RBLs to block spam is less
> effective than not using filters at all or why using RBL's in
> conjunction with content-based filtering isn't more effective than using
> either alone. You may be right, but I'd like to understand why.
Not all RBLs, just open relay RBLs. If you use Open relay rbls, then you
are blocking based on the connection address. This is wrong. You should be
filtering against the IP addresses in the headers of the message. If you
filter this way, the relay used by the spam is irrelevant. It doesn't
matter if the relay is open or closed.
The only people the open relay rbls "help" are those who previously had no
filters at all. Even then, they mostly just get a "feel good". Much the
"blocked spam" is originated by the open relay people.
Using RBL's (on the headers) in conjunction with content filters is a good
thing.
--Dean
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