public blacklists

[Scot L. Harris]

On Wed, 2004-12-08 at 12:09, David Mackintosh wrote:
> On Wed, Dec 08, 2004 at 11:56:25AM -0500, Scot L. Harris wrote:
>  
> > Greylisting does not even incur the network overhead of using rbls, it
> > issues a temporary reject on the message.  A real MTA will retry after a
> > few minutes (sometimes longer) but the spam zombies won't retry.  As a
> > result most spam gets dropped before you even receive the message.
> 
> Greylisting is good, as long as you control all your MX systems. 
> Most of our small clients use an ISP for a secondary MX, and our
> experience shows that the majority of spam is aimed at that MX.
> Greylisting won't help you there, as the secondary MX will obediently
> retry after your timeout.

I think that should be understood as a given. :)  If there is a backdoor
to get into your email systems and it is not protected by the same tools
then spam will get through.  Same is true for spamassassin, if you have
that on your main email server but not on your backup system spam will
not get flagged or dumped to the spam bucket.

-- 
Scot L. Harris
webid at cfl.rr.com

Your reasoning is ............................. (fill in the blank)

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